Materials Science
Mechanism-Resolved PFM of Ferroionic and Ferroelectric Responses in Thickness-Gradient Hf0.5Zr0.5O2 Libraries
Yu Liu, Yi-Xiu Chen, Haotong Liang et al. (+2 more)
Resolving growth mechanisms and thickness
evolution of functional properties is one of the key tasks in materials discovery and optimization involving thin-film materials, traditionally requiring significant experimental budgets. Here we introduce the combination of thickness-gradient libraries and automated scanning probe microscopy as a systematic pathway to elucidate growth modes and disentangle ferroelectric and electrochemical contributions in ferroelectric thin films. As a model system, we explore the Hf0.5Zr0.5O2 (HZO) gradient thin films grown on LaxSr1-xMnO3 (LSMO) bottom electrode thin films. Automated piezoresponse force microscopy, spectroscopy, and lithography reveals that irreversible topographic deformation arises from electrochemical activity at the LSMO surface, whereas reversible phase inversion in HZO reflects ferroelectric switching. Automated topography height-map scans are used to further quantify nucleation density, particle-size
evolution, and roughness correlations across the thickness-gradient, demonstrating that improved plume stabilization during growth suppresses interfacial reactions and promotes dense, fine-grained HZO conducive to ferroelectric phase formation. This combined materials-engineering and automated-SPM framework establishes a platform for high-throughput, mechanism-resolved characterization of ferroionic and ferroelectric responses in complex
oxide films.
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All authors Yu Liu, Yi-Xiu Chen, Haotong Liang, Ichiro Takeuchi, Sergei V. Kalinin
Materials Science
Spin dynamics of the spin-1 triangular lattice Heisenberg antiferromagnet K$_2$Ni(SeO$_3$)$_2$
Chaebin Kim, Sathvik Nallapati, E. A. Ghioldi et al. (+6 more)
Strong
quantum fluctuations and unconventional
spin dynamics are well established in the
spin-1/2 triangular
lattice Heisenberg antiferromagnet. However, their survival in the
spin-1 case remains an open question. We investigate the
spin dynamics of K$_2$Ni(SeO$_3$)$_2$, a nearly ideal
spin-1 triangular
lattice Heisenberg antiferromagnet, using inelastic
neutron scattering. Below the ordering temperature $T_{\rm N}$, we observe coherent one-
magnon excitations coexisting with a broad high-energy continuum. Two complementary approaches, a spectrally consistent $1/S$-corrected
spin wave theory and a beyond-mean-field Schwinger
boson theory, reproduce different facets of the continuum. Neither alone is complete, demonstrating substantial
quantum fluctuations survive for $S\!=\!1$ and are reflected primarily in the spectral distribution of the continuum. Above $T_{\rm N}$, the continuum bandwidth is conserved while spectral weight is redistributed as
magnons lose spatial coherence. Our results establish K$_2$Ni(SeO$_3$)$_2$ as a model triangular antiferromagnet, identifying bandwidth conservation and the distribution of spectral weight within the continuum as organizing principles to understand the
spin dynamics of ordered
quantum magnets beyond
spin-1/2. Our results highlight the need for controlled calculations of the interacting multi-
magnon sector of 2D antiferromagnets.
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All authors Chaebin Kim, Sathvik Nallapati, E. A. Ghioldi, Long Chen, Alexander I. Kolesnikov, Haidong Zhou, Shang-Shun Zhang, Cristian D. Batista, Martin Mourigal
Soft Condensed Matter
Duality of Theories for the Electrical Double Layer in Concentrated Electrolytes
Zachary A. H. Goodwin
Understanding the electrical double layer (EDL), i.e, the distribution of electrolyte at an electrified interface, in concentrated electrolytes is important for various technologies, such as supercapacitors, batteries and electrocatalysis. Atomistic approaches offer unprecedented detail, but are too computationally expensive to exhaustively investigate the EDL of concentrated electrolytes, motivating the development of continuum theories. In these concentrated electrolytes, correlations between ions and solvents are strong, through electrostatic and specific interactions, as well as significant excluded volume effects of the complicated molecular species, making the development of theories challenging. Thus far, there are mainly two distinct simple theoretical approaches to understand the EDL of concentrated electrolytes, with account of these correlations beyond mean-field. One is a local-density approximation (LDA) based on treating electrostatic and specific interactions beyond mean-field through the ionic aggregation and solvation; where a simple conceptual understanding can be gained and reasonable agreement with experiments in terms of integrated quantities, but poor agreement for ion profiles and Debye capacitance. The other approach is to treat electrostatic correlations and excluded volume effects more rigorously with beyond LDA approaches, but at the cost of simplifying the chemical interactions between species; where excellent agreement can be obtained for ion profiles, differential capacitance, etc., but mainly for the simplified hard-sphere systems that the theories are based on. Here, we describe the merits and downfalls of these two approaches, how they have contributed to understanding anomalous underscreening, and outline future directions for these theoretical approaches.
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Strongly Correlated Electrons
Vacancy-induced local moments in quantum paramagnetic phases: An SU($N$) designer Hamiltonian study
Md Zahid Ansari, Souvik Kundu and Kedar Damle
We explore the effects of non-
magnetic impurities (vacancy disorder) on the
quantum paramagnetic phases stabilized by SU($N$) designer
Hamiltonians on bipartite
lattices. Using the results of our
quantum Monte Carlo simulations, we demonstrate that isolated vacancies seed emergent
spin $S=1/2$ moments in their vicinity when the low-temperature state has valence bond solid order. Indeed, our
quantum Monte Carlo results for the low-temperature susceptibility in such regimes shows clear evidence of the vacancy-induced Curie tails associated with these emergent moments, and our zero-temperature projector Monte Carlo results on the ground-state wavefunction in the valence bond basis provide additional evidence in support of this picture. Further, for such designer
Hamiltonians on the Lieb
lattice with two additional sites on each bond of a square
lattice, we identify a low-temperature
spin liquid-like regime with no sign of
spin or valence bond order. This
liquid-like regime serves as a test bed for validating a recently-developed argument concerning the effects of vacancy disorder in such low temperature regimes. Consistent with this argument, we find that isolated vacancies do not seed emergent local moments in such
spin liquids. Instead, in the presence of vacancy disorder, emergent local moments are associated with the presence of monomers in maximum-density dimer packings of the corresponding diluted
lattice.
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Superconductivity
A Kapitza Pendulum Route to Supercurrent Tunnel Diodes
Yuriy Yerin, Stefan-Ludwig Drechsler, A. A. Varlamov et al. (+3 more)
Superconducting diodes that support nonreciprocal supercurrent flow in principle constitute attractive, non-dissipative,
circuit elements for superconducting electronics. But their realization faces fundamental challenges, as conventional Josephson tunnel junctions are inherently reciprocal. Existing approaches to break reciprocity typically involve magnetism or
spin-orbit coupling, which often increase device complexity and limit reproducibility. Here, we demonstrate an alternative dynamical route to supercurrent nonreciprocity based on parametric driving. By applying a frequency-modulated supercurrent amplitude we show that effective higher-order, nonharmonic terms are generated in the current-phase relation. Leveraging mathematical equivalences with the Kapitza pendulum, we show that these terms dynamically break reciprocity. This establishes the concept of a Kapitza supercurrent diode and demonstrates that nonreciprocal superconducting transport can be engineered by nonequilibrium driving conventional Josephson tunnel junctions. We propose two implementations of the Kapitza supercurrent diode - via gate-controlled superconducting interferometers or flux-driven double-loop SQUIDs - to achieve nonreciprocal supercurrent transport within experimentally accessible frequencies $\omega/2\pi \sim 1$-$10\,\mathrm{GHz}$.
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All authors Yuriy Yerin, Stefan-Ludwig Drechsler, A. A. Varlamov, Francesco Giazotto, Jeroen van den Brink, Mario Cuoco
Mesoscale and Nanoscale Physics
Tuning the memristive response of TaO$_x$-based devices with Ag Nanoparticles
R. Leal Martir, A.J.T. van der Ree, M. H. Aguirre et al. (+3 more)
Defect engineering is a key strategy to control resistive switching (RS) in
oxide-based memristive devices, where oxygen vacancy (OV) dynamics governs filament formation and rupture. We investigate the effect of Ag nanoparticles (AgNPs) embedded in the top electrode of Pt/Ta2O5/TaO2/Pt memristors and analyze their RS behavior and statistical stability. Devices without AgNPs exhibit two hysteresis switching loops (HSLs) with opposite chiralities, originating from the participation of the Pt/Ta2O5 top interface and the Ta2O5/TaO2 bottom interface. Incorporating AgNPs reduces the overall device resistance and selectively suppresses one loop, yielding a single, well-defined switching mode. Moreover, devices incorporating Ag-NPs show markedly reduced cycle-to-cycle variability of the high-resistance state, as confirmed by Weibull analysis, indicating improved endurance and switching reproducibility. Within a filamentary RS framework, we attribute this behavior to local metallization of the top interface by AgNPs, which partially inhibit OV transport and confines the RS dynamics to the bottom interface. Numerical simulations with the Oxygen Vacancy Resistive Network (OVRN) model succesfully reproduce the experimental HSLs, statistical trends, and tunable ON/OFF ratios with AgNPs coverage. These findings demonstrate that targeted interface metallization via metallic nanoparticles provides an effective route to control multi-interface RS dynamics and improve switching stability in without modifying the
oxide architecture.
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All authors R. Leal Martir, A.J.T. van der Ree, M. H. Aguirre, G. Palasantzas, D. Rubi, M. J. Sánchez
Mesoscale and Nanoscale Physics
Thermal Casimir Force Imaging of Nonequilibrium Hot Electrons
Weikang Lu, Ziyi Xu, Hewan Zhang et al. (+11 more)
The thermal Casimir effect, arising from fluctuating electromagnetic fields of thermally agitated charges, induces thermosensitive forces and presents a novel approach to detecting nanoscale hot electrons, elusive yet ubiquitous in modern miniaturized transistors. However, detecting thermal Casimir forces at the nanoscale remains extremely challenging due to background forces such as electrostatic force and
quantum Casimir force. In this study, we present the first non-contact force measurement of hot electrons based on the thermal Casimir effect. Using an atomic force microscope (AFM) with a dual-resonant tip, we achieve thermosensitive force detection of nonequilibrium hot electrons while effectively suppressing background thermo-insensitive forces, thereby distinguishing them from cold electrons. In silicon nanoconstriction devices, the measured thermal Casimir pressure reaches approximately 3 bar at a separation of 5 nm at an electron temperature of about 10^3 K. Our work introduces a novel methodology for hot electron nanothermometry and provides critical insights into the thermo-mechanical properties of post-Moore nanoelectronics.
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All authors Weikang Lu, Ziyi Xu, Hewan Zhang, Svend Age Biehs, Achim Kittel, Ludi Qin, Xue Gong, Huanyi Xue, Yanru Song, Zhengyang Zhong, Shiyou Chen, Kun Ding, Wei Lu, Zhenghua An
Strongly Correlated Electrons
A Unified Approach to Strong Local Correlations and Collective Fluctuations: Eliminating Divergence in the Spin Channel
S.D. Semenov, A.I. Lichtenstein and A.N. Rubtsov
Dynamical mean-field theory (DMFT) provides an optimal local approximation for correlated
lattice systems by mapping the
lattice onto a self-consistent effective
impurity model. To account for the missing long-range correlations, we propose a novel extended approach, which we term fluctuating dynamical mean-field theory (fDMFT). It incorporates collective fluctuations of auxiliary
impurity models across different sites via functional integration. Technically, this method involves obtaining a family of DMFT solutions on a grid for a self-consistent auxiliary classical field applied to the
lattice. While the result can, in principle, be improved diagrammatically, we find that the minimal version of the theory already yields accurate results, with lowest-order diagrammatic corrections offering only minor improvements. This consistent framework, based on our fluctuating local field concept, demonstrates superior performance for the nearly half-filled Hubbard model compared to other known diagrammatic extensions of DMFT.
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Materials Science
Dirac semimetal phases in chiral carbon nanoscrolls
Tzu-Ching Hsu, Jhih-Shih You, Hsiu-Chuan Hsu et al. (+1 more)
Chirality induced by rolling a two-dimensional material into a spiral geometry reshapes its electronic band structure. In this work, we theoretically investigate the topological properties of carbon nanoscrolls under an axial
magnetic field, focusing on structures in which chirality is encoded through shifted edge
alignments. In contrast to unshifted structures, where mirror
symmetry pins the Dirac cones to half a flux
quantum,
chiral carbon nanoscrolls lack this
symmetry, and Dirac cones emerge at
magnetic flux values away from half a flux
quantum. We demonstrate that these Dirac cones are topologically protected by combined inversion-time reversal
symmetry and remain robust even when sublattice
symmetry is broken. Furthermore, we show that the number of Dirac cones and their real-space probability distributions depend on the number of turns and the
magnetic field strength. Our study elucidates the role of chirality in the band
topology of nanoscroll geometries.
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All authors Tzu-Ching Hsu, Jhih-Shih You, Hsiu-Chuan Hsu, Ion Cosma Fulga
Strongly Correlated Electrons
Spontaneous Fully Compensated Ferrimagnetism
Bingbing Wang, Yongpan Li, Yichen Liu et al. (+1 more)
We propose a general mechanism for the spontaneous emergence of filling-enforced fully compensated ferrimagnetism (fFIM), characterized by zero net magnetization yet
ferromagnetic-like
spin-split band structures. Using Hartree-Fock mean-field calculations of the Hubbard model, we map out the stability regime of spontaneous fFIM over a broad parameter space of interaction strength and staggered potential. We show the unique
quantum-geometry-governed optical selection rules and the abundant valley- and
spin-related physics of electronics and optics arising from the emergence of fFIM order, with tunable
spin-polarized and valley-contrasting charge and
spin currents. Furthermore, based on our theory, we demonstrate that spontaneous fFIM can be realized in nominally nonmagnetic
graphene via defect engineering. Our results establish a unified framework for the mechanism, emergent properties, and materials realization of spontaneous fFIM, opening new opportunities for spintronic, valleytronic, and optoelectronic applications.
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All authors Bingbing Wang, Yongpan Li, Yichen Liu, Cheng-Cheng Liu
Soft Condensed Matter
MesoMem: A mesoscale membrane model based on an additive potential
Pietro Sillano, Siewert-Jan Marrink and Timon Idema
Bridging the gap between atomistic detail and continuum mechanics is a central challenge in modeling biological membranes, particularly for mesoscopic phenomena spanning large length and time scales. In this work, we introduce a new, solvent-free, one-particle-thick, coarse-grained model for lipid
bilayers, governed by an additive potential. Our approach treats orientational elasticity through distinct additive energy terms for tilt and splay, offering an unbiased potential form. The model is implemented in the LAMMPS molecular dynamics engine. Our simulations show spontaneous self-assembly of lamellar structures and stable vesicles from disordered states. We map the dynamical phase diagram of the system, identifying distinct gel-like, fluid, and gas regimes, controlled by temperature and the steepness of the isotropic attraction. The model accurately reproduces the theoretical $1/q^{4}$ fluctuation spectrum for tensionless membranes and exhibits tunable mechanical properties, including biologically relevant bending
rigidities. We show how we can include osmotic pressure and spontaneous
curvature in our model. Finally, we demonstrate the model's applicability to complex membrane remodeling by simulating the adhesive wrapping of colloidal nanoparticles, recovering the predicted dependency on particle size and adhesion strength.
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Mesoscale and Nanoscale Physics
Microwave response of fractional quantum Hall droplets with quasiparticle tunneling
Fumihiro Murabayashi, Ryotaro Sano, Flavio Ronetti et al. (+4 more)
We theoretically study microwave absorption spectroscopy of fractional
quantum Hall droplets in the presence of quasiparticle tunneling across a
quantum point contact. This contact-free probe provides access to collective edge dynamics beyond conventional transport measurements. We develop a nonperturbative path-integral Monte Carlo approach that enables computation of the frequency-dependent response at finite temperature and for arbitrary droplet geometries, and
benchmark the method against analytical results in the weak-tunneling regime. We find that tunneling produces measurable shifts and broadening of resonance peaks, with systematic dependence on tunneling strength and device geometry. Such shifts and broadenings are not obtained in perturbative treatments acting directly on the response function, but emerge when interaction-kernel effects are properly incorporated. Our results indicate experimentally accessible signatures of edge-mode interference and tunneling-induced renormalization of collective excitations, and support the use of microwave spectroscopy as a quantitative probe of quasiparticle dynamics in mesoscopic
quantum Hall structures.
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All authors Fumihiro Murabayashi, Ryotaro Sano, Flavio Ronetti, Jérôme Rech, Thierry Martin, Thibaut Jonckheere, Takeo Kato
Materials Science
Synthesis and Structural Analysis of an Emissive Colloidal Argyrodite Nanocrystal: Canfieldite Ag8SnS6
Francisco Yarur Villanueva, Victor Quezada Novoa, Pascal Rusch et al. (+12 more)
We resolve a phase identification controversy in the Ag-Sn-S material system by unraveling the polymorphic structure of nanocrystals within the argyrodite material family. Argyrodites are a class of superionic materials used in their bulk form for applications in solid-state batteries and thermoelectrics, where their advantageous properties relate to their polymorphism. However, despite their well-studied bulk applications, the limited exploration at the nanoscale has left considerable potential for the discovery of emerging properties due to size effects. Further, phase identification presents a prominent challenge to the study of polymorphs in superionic conductors and related mate-rials. In this work, we synthesize canfieldite-like (Ag8SnS6) nanocrystals to understand their formation and structural behavior at the nanoscale. We observe the emergence of emissive, meta-stable, cluster-like species. Then, high-resolution transmission electron microscopy reveals indistinguishable polymorphs of canfieldite due to identical heavy-atom frameworks. However, using synchrotron X-ray total scattering for pair distribution function analysis, we uncover structural distortions, showing a pseudo-orthorhombic configuration that likely gives rise to the red emission. Further, we investigate the optical properties and structure of Ag8SnS6 nanocrystals upon the addition of Zn2+, the cation of interest in the canfieldite vs. pirquitasite (Ag2ZnSnS4) phase identification controversy. We show that Zn2+ is incorporated in the canfieldite-like structure through the replacement of Ag+, boosting the emission. Our results solve a standing phase identification challenge and uncover fundamental insights for the synthesis and structure of canfieldite nanocrystals, laying the ground for the exploration of other argyrodite materials with emerging properties at the nanoscale.
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All authors Francisco Yarur Villanueva, Victor Quezada Novoa, Pascal Rusch, Stefano Toso, Maxwell W. Terban, Yurii P. Ivanov, Joaquin Carlos Chu, Maxine J. Kirshenbaum, Ehsan Nikbin, Maria J. Gendron Romero, Mirko Prato, Giorgio Divitini, Jane Y. Howe, Mark W.B. Wilson, Liberato Manna
Other Condensed Matter
Real-Time Formation of a Landau Polaron
Priya Nagpal, Arnab Ghosh, Helene Seiler et al. (+2 more)
Polarons are electronic excitations dressed by a self-consistent
lattice distortion, yet their formation has not been directly resolved in real time. We develop a microscopic lineshape framework that connects the growth of a collective
lattice polarization to the population-time
evolution of the anti-diagonal linewidth in coherent multidimensional spectroscopy. Within this formalism, the anti-diagonal linewidth directly tracks the decay of
lattice frequency-frequency correlations. Underdamped
phonon environments produce oscillatory linewidth modulation, whereas overdamped collective polarization dynamics generate monotonic exponential broadening. Applying this framework to multidimensional measurements on perovskite
quantum dots, we show that the observed approximately 150 femtosecond exponential anti-diagonal broadening reflects the decay of a collective polarization order parameter. These results establish anti-diagonal linewidth dynamics as a direct real-time signature of Landau polaron formation.
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All authors Priya Nagpal, Arnab Ghosh, Helene Seiler, Samuel Palato, Patanjali Kambhampati
Mesoscale and Nanoscale Physics
Integrated nanophotonic platform for on-chip quantum emitter interactions and entanglement
Yinhui Kan, Shailesh Kumar, Xujing Liu et al. (+2 more)
Entanglement between solid-state
quantum emitters (QEs) is a key resource for photonic
quantum technologies. Achieving such
entanglement requires strong and controllable long-range interactions between QEs. However, engineering such coupling remains challenging, particularly for on-chip distant solid-state QEs. Here, we introduce a forward-designed platform that enables ultracompact nanophotonic architectures to mediate enhanced long-range QE-QE interactions via engineered surface plasmon polariton interference. Using this strategy, we realize two distinct configurations: a phase-conjugated
elliptic design for energy funneling, and a co-radiating
hyperbolic design for its suppression. We experimentally demonstrate large enhancement and suppression of energy transfer rates compared to bare substrates. Furthermore, we predict transient
entanglement between spatially separated QEs with concurrence peaking at 0.493, approaching the theoretical bound in the transient regime. Extending to the multi-QE case, we observe enhanced energy funneling and predict QE-QE
entanglement in three-QE configurations. These results establish a compact and scalable framework for on-chip
entanglement engineering in integrated
quantum nanophotonic systems.
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All authors Yinhui Kan, Shailesh Kumar, Xujing Liu, Antonio I. Fernández-Domínguez, Sergey I. Bozhevolnyi
Superconductivity
Highly-linear flux-to-voltage transducer based on superconducting quantum interference proximity transistors
Angelo Greco, Giorgio De Simoni and Francesco Giazotto
Superconducting
quantum interference devices (SQUIDs) are state-of-the-art in ultra-sensitive magnetometry; however, conventional SQUID devices are fundamentally limited by the inherently nonlinear and periodic nature of their transfer function. Although flux-locked loop (FLL) configurations can mitigate this issue, they introduce electronic complexity and bandwidth constraints that hinder scalability in
quantum circuits. In this work, we present an experimental demonstration of the bi-SQUIPT, a flux transducer that modulates the density of states in a proximitized superconducting weak link. The device employs a dual-loop architecture with differential readout, which enables cancellation of non-linearities typical of individual elements, achieving a voltage swing of approximately 120 $\mu$V. Measurements yield a spurious-free dynamic range (SFDR) of up to 60 dB, consistent with theoretical predictions and comparable to that of SQUID arrays, while maintaining power dissipation in the femtowatt range. The results further highlight a remarkable operational stability up to 600 mK, positioning the bi-SQUIPT as an enabling technology for high-density cryogenic
quantum electronics.
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Materials Science · Cross-listed from physics.optics
All-optical control of second-harmonic generation in $\beta$-BaB$_2$O$_4$ via coherent, terahertz-driven acentric lattice displacement
Flavio Giorgianni, Nicola Colonna, Gabriel Nagamine et al. (+6 more)
Dynamical control of the nonlinear optical properties of solids – with light itself – will be essential for future ultrafast photonic technologies. Previously, methods to modulate nonlinear processes including second-harmonic generation (SHG) have relied primarily on non-resonant light-matter interaction or photo-generation of hot electrons in nanoscale materials. However, these approaches are typically constrained by limited interaction lengths and the initial frequency conversion is relatively weak under
equilibrium conditions. Here, an approximately 30% modulation of efficient phase-matched SHG in bulk beta-barium borate (beta-BaB2O4) is achieved through transient
lattice deformation by intense terahertz (THz) pulses that are tuned to resonance with an infrared-active
phonon mode. The effect originates from modification of the index of refraction ellipsiod and the corresponding nonlinear phase-matching conditions, rather than from direct modulation of the nonlinear susceptibility through THz-mediated chi^(3) processes. This mechanism, of resonant selective
lattice excitation, points toward novel THz-control schemes to tune the nonlinear optical response in materials.
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All authors Flavio Giorgianni, Nicola Colonna, Gabriel Nagamine, Leonie Spitz, Guy Matmon, Alexandre Trisorio, Nicolas Forget, Carlo Vicario, Adrian L. Cavalieri
Materials Science
Interfacial Oxidation Enables Charge-Transfer Contacts and Degenerate n-Doping in Monolayer MoS$_2$
Marco Bianchi, Daniel Lizzit, Alberto Turoldo et al. (+7 more)
High contact resistance remains a central obstacle to the integration of two-dimensional (2D)
semiconductors in electronic devices. Recent advances have demonstrated that contact performance can be dramatically improved through interface engineering, including the use of group-V semimetals and charge-transfer contacts based on strong interfacial doping. Here, we show that controlled interfacial oxidation provides an effective route to convert a semimetal contact into a charge-transfer contact that degenerately $n$-dopes single layer MoS$_2$. Using a combination of angle-resolved photoemission spectroscopy, X-ray photoelectron diffraction, low-energy electron diffraction and scanning tunnelling spectroscopy, we demonstrate that putting single layer MoS$_2$ in contact with a pristine Bi layer merely results in weak doping, whereas oxidation of the Bi layer leads to a pronounced occupation of the MoS$_2$ conduction band with an electron density on the order of $10^{13}$~cm$^{-2}$. The cause of this strong electron doping is the fact that an ultrathin $\beta$-Bi$_2$O$_3$ layer forms below the MoS$_2$ and that this has a particularly low work function, thereby acting as an efficient electron donor to MoS$_2$. Interfacial oxidation thus emerges as a powerful design knob for engineering charge-transfer contacts to 2D
semiconductors.
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All authors Marco Bianchi, Daniel Lizzit, Alberto Turoldo, Ezequiel Tosi, Paolo Lacovig, Monika Schied, Davide Curcio, Charlotte E. Sanders, Silvano Lizzit, Philip Hofmann
Soft Condensed Matter
Solubilization kinetics of oils by ionic and nonionic micelles: theoretical model
Alexey Kabalnov
Experimental data on solubilization kinetics found in literature were analyzed by using the model proposed earlier (1). The rates of oil molecular exchange between the micellar core and the surrounding aqueous solution were determined. It was concluded that the solubilization of hydrocarbon molecules by nonionic surfactants of ethylene
oxide type is essentially barrier-free, that is, is
diffusion controlled. It is quite different for ionic surfactants, where the rate is one-two orders of magnitude slower, indicating the existence of a potential barrier for hydrocarbons to get inside the micelles. A Fickean
diffusion model of solubilization has been proposed to explain these trends. For ionic micelles, the hydrocarbons are predicted to be excluded from the micellar double layer region because of their low dielectric constant. The Poisson-Boltzmann model was used to model this effect; the
diffusion retardation factors were compared with the experiment and a fair agreement was seen. For nonionic groups, such as oligoethylene
oxide, on the other hand, no such barrier was predicted to exist. The analysis of this paper is performed only for the case of the 'slow' solubilization; it does not cover the case of the rapid, 'catastrophic' solubilization observed in the other group of experiments; the distinction between the slow and fast mechanisms is discussed and a possible explanation is suggested.
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Strongly Correlated Electrons
Emergence of geometric order from topological constraints in a three-dimensional Coulomb phase
Benjamin Canals
The emergence of order and
geometric limit shapes in a three-dimensional (3D) Coulomb phase subject to domain wall boundary conditions (DWBC) is investigated. While the arctic circle phenomenon – the spatial segregation of frozen and fluctuating degrees of freedom – is well-established in the two-dimensional six-vertex model (square ice), its extension to 3D remains largely unexplored. A cubic
lattice model with Ising degrees of freedom living on the edges, whose ground state
manifold is governed by a divergence-free (3-in/3-out) local constraint, is considered. In the bulk, this model realizes a classical
spin liquid characterized by algebraic correlations and pinch-point singularities in reciprocal space. It is demonstrated that applying DWBC partially lifts the extensive ground state degeneracy, inducing long-range
magnetic order in the thermodynamic limit. Despite this ordering, it is found that the system retains a fluctuating component that exhibits the signature of a Coulomb phase. Finally, by mapping the local vertex polarization density, compelling numerical support is provided for a 3D generalization of the arctic limit shape, bridging the gap between topological constraints and emergent geometry in higher dimensions.
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Mesoscale and Nanoscale Physics
Nanoelectronics with Two Dimensional Magnets
Bing Zhao, Roselle Ngaloy, Lalit Pandey et al. (+3 more)
Two dimensional (2D) magnets have emerged as a compelling platform for
spin based nanoelectronics, enabling atomic scale control of
magnetic order, interfaces,
quantum geometry, and
symmetry. Here, we highlight recent advances in 2D ferromagnets, antiferromagnets, altermagnets, and related
magnetic phases, emphasizing how enhanced Curie temperatures, perpendicular
magnetic anisotropy, and unconventional
magnetic orders translate into device relevant functionality.
Spin dependent transport in vertical
magnetic tunnel junctions and lateral
spin valves based on 2D
heterostructures are discussed, where atomically sharp interfaces enable highly tunable
spin injection, propagation, and detection. We further focused on field free energy efficient
spin orbit torque magnetization switching in 2D
magnetic heterostructures, in which unconventional
spin currents originate from an adjacent low
symmetry spin orbit layer. Microscopic mechanisms involving
symmetry breaking, Berry
curvature, and orbital angular momentum transport are discussed, along with key challenges, including switching determinism and torque efficiency. Materials and device design strategies targeting neuromorphic, hybrid
quantum spintronic, and multifunctional architectures are outlined. Collectively, these developments position 2D magnets as a promising candidate for tunable, energy efficient integrated spintronic technologies that can harness intertwined
spin, charge, orbital, and topological degrees of freedom at the nanoscale.
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All authors Bing Zhao, Roselle Ngaloy, Lalit Pandey, Himanshu Bangar, Divya P. Dubey, Saroj P. Dash
Materials Science
Fermi-surface studies of altermagnetic CrSb from Shubnikov-de Haas oscillations
Sajal Naduvile Thadathil, Beat Valentin Schwarze, Jaafar Ansari et al. (+14 more)
Within the family of altermagnets, CrSb is a metallic, collinearly ordered material that exhibits particularly strong
symmetry-induced
spin splitting in its band structure. In this study, we combine electrical magnetotransport measurements up to 68 T on microfabricated single-crystalline CrSb with first-principles calculations to investigate its
Fermi surface. Notably, we study the temperature and field-orientation dependence of
magnetic quantum oscillations observed in the magnetoresistance. The observed frequency spectrum agrees well with results from density-functional-theory calculations. Our results confirm the predicted electronic band structure of altermagnetic CrSb and highlight the importance of high
magnetic fields for accurately mapping the
Fermi surfaces of unconventional emergent materials.
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All authors Sajal Naduvile Thadathil, Beat Valentin Schwarze, Jaafar Ansari, Tommy Kotte, Sven Luther, Marc Uhlarz, Freya Husstedt, Rafael Gonzalez-Hernandez, Libor Šmejkal, Thanassis Speliotis, Markéta Žáčková, Jiří Pospíšil, Christoph Müller, Dominik Kriegner, Helena Reichlová, Joachim Wosnitza, Toni Helm
Superconductivity
Superconductivity in the A15-type V3(Os1-2xSixGex) medium-entropy alloys
Yucheng Li, Kuan Li, Lingyong Zeng et al. (+4 more)
Cubic A15-type superconducting
alloys continue to fascinate the academic and industrial fields because they mainly support the largest
market for low-temperature superconducting applications and show exotic physical properties. Medium-/high-
entropy alloys (MEAs-HEAs) can be employed stably under extreme conditions due to their high mechanical hardness and excellent irradiation tolerance. Combining with the features of the A15-type
superconductor and MEAs-HEAs, we design a series of previously unreported A15-type V3(Os1-2xSixGex) (x = 0.333, 0.375, 0.425) MEA
superconductors, which can be obtained by an arc melting method. Resistivity,
magnetic susceptibility, and specific heat measurements indicate that all of them are type-II bulk
superconductors. The superconducting transition temperature (Tc) exhibits an upward trend with the systematic reduction of Os concentration. Additionally, the upper critical field of the V3(Os0.333Si0.333Ge0.333) sample is larger than the Pauli limit, suggesting it may be robust against
magnetic fields due to
spin-orbit coupling induced by the heavy Os atoms. These findings not only advance our understanding of emergent phenomena in
entropy-stabilized A15-type
alloys but also expand the members of new
superconductors.
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All authors Yucheng Li, Kuan Li, Lingyong Zeng, Rui Chen, Jingjun Qin, Shuangyue Wang, Huixia Luo
Statistical Mechanics
Exact Anomalous Current Fluctuations in Quantum Many-Body Dynamics
Kazuya Fujimoto, Taiki Ishiyama, Taiga Kurose et al. (+2 more)
Fluctuations of integrated currents have attracted considerable interest over the past decades in the context of statistical mechanics. Recently, anomalous current fluctuations, characterized by the M-Wright function, were obtained exactly in a classical automaton [$\v{Z}$. Krajnik et al., Phys. Rev. Lett. 128, 160601 (2022)], and previous studies have shown that the anomalous behavior can arise in a variety of classical systems. Despite the rapidly growing interest in such anomalous behaviors, which capture a universal aspect of one-dimensional many-body transport, the exact derivation of the M-Wright function in
quantum many-body systems has remained elusive. In this Letter, we present the first exact microscopic derivation of the M-Wright function in
quantum many-body dynamics by analyzing the integrated
spin current in a one-dimensional
Fermi-Hubbard model with infinitely strong repulsive interactions. Our results lay the groundwork for exploring anomalous integrated currents in a broad class of
quantum many-body systems.
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All authors Kazuya Fujimoto, Taiki Ishiyama, Taiga Kurose, Takato Yoshimura, Tomohiro Sasamoto
Quantum Gases
Fulde-Ferrell superfluids in an asymmetric three-component Fermi Gas
Yuhan Lu, Lihong Zhou and Yongping Zhang
An asymmetric three-component
Fermi gas, featuring Raman-induced
spin-orbit coupling between the first and second components and contact interaction only between the first and third components, introduces both
spin-orbit coupling and population imbalance-two mechanisms known to stabilize the Fulde-Ferrell superfluids.We systematically study Fulde-Ferrell superfluids in an asymmetric three-component
Fermi gas { in two dimensions and at zero temperature} by finding the global minima of the thermodynamic potential. We reveal a new class of composite Fulde-Ferrell superfluids that emerges when strong
spin-orbit coupling generates a double-well structure in momentum space within the lower
spin-orbit-coupled band. The key features of these composite superfluids are identified.
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Strongly Correlated Electrons
Triplon-mediated pairing and the superconducting gap structure in bilayer nickelates
Huimei Liu and Giniyat Khaliullin
We investigate the superconducting gap structure in
bilayer nickelates within a model in which conduction bands of dx2-y2
symmetry coexist with localized d3z2-r2
spins. Strong interlayer coupling drives the local moments into a singlet ground state, whose virtual singlet-triplet excitations ("triplons") mediate the pairing interaction. This mechanism yields interband s+- pairing, with opposite signs of the order parameter on the two (alpha and beta) bands. The calculated tunneling spectra reproduce the recently observed two-peak structure, the larger gap on the alpha band despite its smaller density of states, and the gap anisotropy. The results provide strong evidence for the triplon-mediated pairing mechanism in
bilayer nickelates.
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Statistical Mechanics
Information bound on navigation speed in smart active matter
Kristian Stølevik Olsen, Mitsusuke Tarama and Hartmut Löwen
Intelligent behavior in life-like systems often arises from the ability to gather, process, and act on information. While active matter provides a framework for studying life-like dynamics, it typically omits internal information-processing and decision-making. Here we introduce an adaptive active particle model that uses minimal information processing capabilities in order to navigate towards a distant target. By combining renewal-based intermittent motion with the Cramér-Rao inequality, we derive a bound on the
navigation speed valid for a wide range of information processing strategies. The framework captures hallmark features of cognitive systems, including optimal sensing durations and a speed-accuracy trade-off that balances noise and reliability. Allowing stored information to degrade before action reveals that although deterioration slows
navigation, the trade-off remains governed primarily by external orientational noise and is remarkably insensitive to
memory decay.
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Strongly Correlated Electrons
Quantum spin models of commensurate $p$-wave magnets
GiBaik Sim and Stephan Rachel
The $p$-wave magnet has emerged as a new type of magnetism exhibiting odd-parity, time-reversal-symmetric
spin splitting in momentum space, and has attracted considerable interest as a promising platform for spintronic applications. However, the theoretical understanding of the fundamental mechanism responsible for stabilizing this phase remains limited. In this work, we identify a microscopic interacting model that realizes the $p$-wave magnet as its ground state. We first introduce a Hubbard model and derive the corresponding low-energy
spin Hamiltonian. At the classical level, we find that the $p$-wave magnet is stabilized but remains energetically degenerate with competing noncoplanar states.
Quantum fluctuations lift this degeneracy, selecting the $p$-wave magnet as the unique ground state. The resulting electronic structure exhibits finite
spin accumulation via the Edelstein effect, highlighting the potential of $p$-wave magnetism for spintronic applications. We further discuss the relevance of our theory to quasi-two-dimensional honeycomb magnets such as Ni$_2$Mo$_3$O$_8$. Our findings establish the possibility of spontaneous $p$-wave magnetism.
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Mesoscale and Nanoscale Physics
Effect of electron-electron interactions on the propagation of ultrashort voltage pulses in a Mach-Zehnder interferometer
Prasoon Kumar, Thomas Kloss and Xavier Waintal
Electronic interferometers have been identified as possible candidates for building electronic flying
qubits. Such a regime requires ultrafast voltage pulses whose duration is shorter than the time of flight through the device. Understanding the corresponding physics in the presence of such short excitations requires a proper treatment of electron-electron interactions. In this article, we take a step in this direction by performing time-resolved simulations of a Mach-Zehnder interferometer treating the interactions at the time-dependent mean-field level. We find that the main effect of the interaction is the renormalization of the pulse velocity. Very importantly, the interference effects appear to be robust to the presence of interactions.
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Mesoscale and Nanoscale Physics
The temporal picture for Bloch electron dynamics in homogeneous electric fields
G. J. Iafrate and V. N. Sokolov
The transient picture for a Bloch electron accelerating in an arbitrarily time-dependent homogeneous electric field is developed. The temporal sequence for the analysis includes the instant after electron injection, followed by the time required for a small change in electron wavenumber away from initial injection, leading to the final time
evolution over many Bloch periods. The time-dependent behavior is studied using the properties of the Schrödinger equation. The electric field is described through the vector potential gauge, and the instantaneous eigenstates of the Bloch, electric-field-dependent
Hamiltonian are used as basis states in describing the Bloch dynamics in the electric field. For each temporal sequence considered, the solution to the Schrödinger equation is established and comparatively discussed. The expectation value of the momentum is obtained for the special case of first order in a constant electric field; the resulting velocity derived is a field-dependent generalization of the natural Zitterbewegung-like behavior discussed in the recent literature. The early-time and long-time limits of the momentum expectation value and its time derivative demonstrate that the resistance to Bloch acceleration after initial band injection varies from real mass to effective mass dynamics as the electron accelerates through the band under the influence of electric field. This changing inertia from early injection of a free-mass electron is the result of the real mass electron dressing-up into the states of the
crystal to become an effective mass electron. The ramifications of this temporal dressing behavior are discussed in considering the general dynamics of Bloch electrons subject to ultrastrong electric fields.
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