arXiv subjects

Jia-Mian Hu

Publications and source records attributed to Jia-Mian Hu.

At least 19 recordsLinked to original sources

arXiv2026

Flexo-Strain Engineering of Phonons and Ferrons in Thin Films of Van der Waals Ferrielectrics

The influence of the flexoelectric coupling on the fluctuations of electric polarization and elastic strains can lead to the principal changes of the dispersion law of soft optical and acoustic phonons and ferrons in a bulk van der Waals ferrielectric. Since the size, gradient and strain effects determine phase diagrams and polarization behavior in thin films, it is reasonable to assume that the flexocoupling and mismatch strains should have a strong influence on the dispersion of phonons and ferrons in thin ferroelectric films. Using the Landau-Ginzburg-Devonshire approach, in this work we reveal that the dispersion of soft optical and acoustic phonons and ferrons is strongly dependent on the sign and magnitude of elastic strains, which originate from the lattice constants mismatch in thin strained films of van der Waals ferrielectric CuInP2S6. In particular, the frequency of acoustic phonons and ferrons approaches zero at nonzero wavevectors k>k_cr, where the critical value of the wavevector k_cr is determined by the mismatch strain, flexoelectric coupling strength and temperature. Zeroing of the acoustic phonon frequency, that appears with increase of tensile strains, indicates a possible emergence of a spatially modulated incommensurate polar phase induced by the flexo-strain effects. Analytical results, derived in this work, open the way for flexo-strain engineering of soft phonon and ferron dispersion in thin films of van der Waals ferrielectrics.

cond-mat.mtrl-sci↗

arXiv2026

Anomalous Piezoelectricity from Polarization-Dependent Electrostriction in Wurtzites

The piezoelectric coefficient is a third-rank tensor connecting the strain or stress with the electric field or polarization, whereas the electrostriction coefficient is a fourth-rank tensor relating the strain to the square of electric polarization. The electrostriction tensor components in the current literature are often treated as constants independent of polarization, resulting in piezoelectric tensor components that are linearly proportional to polarization and the dielectric susceptibility tensor. Here, we study the electrostriction and piezoelectricity in strongly polar wurtzites, including AlN, Al$_{1-x}$Sc$_x$N, Al$_{1-x}$B$_x$N, GaN, and ZnO. We discover that electrostriction and the elastic modulus in wurtzites are both strongly polarization-dependent, and the piezoelectric coefficient is highly nonlinear with respect to polarization, including the anomalous possibility that decreasing polarization increases the electromechanical strain response. These unusual dependencies of electrostriction and piezoelectric effects on polarization arise from the evolution of a layered reference nonpolar structure toward a tetrahedrally coordinated wurtzite network structure as the polarization increases. The findings have important implications in understanding the thermodynamics of the general class of wurtzite ferroelectrics and in manipulating their piezoelectric and ferroelectric behaviors.

cond-mat.mtrl-sci↗

arXiv2026

Terahertz oscillation of $180^{\circ}$ domain walls in ferroelectric membranes

A fundamentally intriguing yet not well understood topic in the field of ferroelectrics is the collective excitation of domain walls (DWs), with potential applications to DW-based nanoelectronic and optoelectronic devices. Here we use dynamical phase-field simulations to identify the collective modes of an Ising-type $180^{\circ}$ DW in a uniaxially strained BaTiO3 membrane. The membrane, which concurrently functions as a cavity for polarization and acoustic waves, permits cavity-enhanced resonant excitation of polarization waves. The simulation reveals an unconventional DW sliding mode that exhibits a bulk-polarization-charge-driven nonzero resonant frequency in the sub-terahertz (THz) regime with a dynamically changing internal structure during sliding. These features differ from the previously reported zero-frequency DW sliding mode or the surface-polarization-charge-driven DW sliding mode. The effect of strain on the frequency of this unconventional DW sliding mode and other previously known THz DW eigenmodes is investigated by dynamical phase-field simulations and interpreted by eigenmode analysis or analytical calculation in a simplified one-dimensional (1D) system. These results provide new insights into the high-frequency dynamics of ferroelectric DWs and suggest opportunities for realizing strain control of phonon-DW resonance, and more broadly, for discovering and controlling unconventional DW modes in conventional domain patterns with applications to reconfigurable THz and optical devices.

cond-mat.mtrl-sci↗

arXiv2026

Strong coupling between coherent ferrons and cavity acoustic phonons

Coherent ferrons, the quanta of polarization waves, can potentially be hybridized with many other quasiparticles for achieving novel control modalities in quantum communication, computing, and sensing. Here, we theoretically demonstrate a new hybridized state resulting from the strong coupling between fundamental-mode (wavenumber is zero) coherent ferrons and cavity bulk acoustic phonons. Using a van der Waals ferroelectric CuInP2S6 membrane as an example, we predict an ultra-strong ferron-phonon coupling at room temperature, where the coupling strength g_c reaches over 10% of the resonant frequency ω_0. We also predict an in-situ bistable electric-field control of mode-specific ferron-phonon hybridization via ferroelectric switching. We further show that CuInP2S6 allows for reaching the fundamentally intriguing but challenging deep strong coupling regime (i.e., g_c/ω_0>1) near the ferroelectric-to-paraelectric phase transition. Our findings establish the theoretical basis for exploiting coherent ferron as a new contender for hybrid quantum system with strong and highly tunable coherent coupling

cond-mat.mtrl-sci↗

arXiv2026

Multimode magnon-phonon cavity driven by symmetry-locked strain fields

Hybrid magnon-phonon cavities with precise control knobs are highly sought after for coherent energy and signal transduction in solid-state platforms. While strain offers a powerful means to tune magnonic characteristics, extending strain engineering into magnon-phonon hybridization has remained elusive. Moreover, implementing controllable strain at the meso- or nanoscale poses a formidable challenge, as spatial inhomogeneity of strain fields often leads to enhanced damping and reduced coherence, thereby hindering device integration and scalability. Here, we present an epitaxial La0.7Sr0.3MnO3/SrTiO3 (LSMO/STO) heterostructure that exhibits strong coupling between the Kittel magnon and acoustic phonon. Leveraging the emergence of structural domains when STO undergoes a cubic-to-tetragonal phase transition, we create anisotropic local strains at the interface. Remarkably, the anisotropic local strain of less than 0.1 % drives the pronounced splitting of the magnon into three branches. Each branch independently hybridizes with acoustic phonons, forming a matrix of magnon-phonon avoided crossings that underpins multimode transduction and programmable networks in frequency and magnetic field space. An analytical model reveals that the split magnon branches are deterministically locked to the three main crystalline axes, enabling robust, orientation-selective control of the hybridized magnon-phonon spectrum against spatial inhomogeneity. Our results establish designed local strain as an exceptionally sensitive trigger for multimode magnon-phonon hybridization in magnetoelastic oxide heterostructures, and highlight local strain engineering as a viable strategy for designing tunable hybrid magnonic and phononic devices.

cond-mat.mtrl-sci↗

arXiv2026

Machine Learning Enabled Graph Analysis of Particulate Composites: Application to Solid-state Battery Cathodes

Particulate composites underpin many solid-state chemical and electrochemical systems, where microstructural features such as multiphase boundaries and inter-particle connections strongly influence system performance. Advances in X-ray microscopy enable capturing large-scale, multimodal images of these complex microstructures with an unprecedentedly high throughput. However, harnessing these datasets to discover new physical insights and guide microstructure optimization remains a major challenge. Here, we develop a machine learning (ML) enabled framework that enables automated transformation of experimental multimodal X-ray images of multiphase particulate composites into scalable, topology-aware graphs for extracting physical insights and establishing local microstructure-property relationships at both the particle and network level. Using the multiphase particulate cathode of solid-state lithium batteries as an example, our ML-enabled graph analysis corroborates the critical role of triple phase junctions and concurrent ion/electron conduction channels in realizing desirable local electrochemical activity. Our work establishes graph-based microstructure representation as a powerful paradigm for bridging multimodal experimental imaging and functional understanding, and facilitating microstructure-aware data-driven materials design in a broad range of particulate composites.

cond-mat.mtrl-sci↗

arXiv2026

Strain patterning of flexomagnetism

Flexomagnetism, the coupling of magnetic ordering to strain gradients, provides access to novel symmetry-broken magnetic phases that cannot be accessed via uniform strain. However, flexomagnetism is hard to understand because it is extremely difficult to control a spatially varying strain. Here, we develop a top-down strategy to pattern transverse strain gradients using helium ion implantation through a lithographically defined mask. Using epitaxial films of the antiferromagnetic nodal line semimetal GdAuGe, we demonstrate that transverse strain gradients $\partial \varepsilon_{zz}/\partial x$ induce near-room-temperature ferromagnetic response, compared to the retained para or antiferromagnetism for homogeneously strained GdAuGe. We spatially correlate the magnetic response with the regions of largest strain gradient, via magnetic force microscopy and nanobeam x-ray diffraction, respectively, to confirm the flexomagnetic response. Our approach opens new avenues for the precise control of magnetic phases in thin films of quantum materials via a patterned strain gradient.

cond-mat.mtrl-sci↗

arXiv2026

HPC-Driven Modeling with ML-Based Surrogates for Magnon-Photon Dynamics in Hybrid Quantum Systems

Simulating hybrid magnonic quantum systems remains a challenge due to the large disparity between the timescales of the two systems. We present a massively parallel GPU-based simulation framework that enables fully coupled, large-scale modeling of on-chip magnon-photon circuits. Our approach resolves the dynamic interaction between ferromagnetic and electromagnetic fields with high spatiotemporal fidelity. To accelerate design workflows, we develop a physics-informed machine learning surrogate trained on the simulation data, reducing computational cost while maintaining accuracy. This combined approach reveals real-time energy exchange dynamics and reproduces key phenomena such as anti-crossing behavior and the suppression of ferromagnetic resonance under strong electromagnetic fields. By addressing the multiscale and multiphysics challenges in magnon-photon modeling, our framework enables scalable simulation and rapid prototyping of next-generation quantum and spintronic devices.

quant-ph↗

arXiv2026

Gilbert Damping Parameters of Epitaxially-Stabilized Iron Gallium Thin Films from Ferromagnetic Resonance

Iron gallium (FeGa) alloys are excellent rare-earth-free magnetostrictors. Through epitaxial stabilization, the disordered A2 alloy can be extended from 19% to 30% gallium resulting in a magnetostrictive coefficient almost twice than that which is seen in rare earth magnetostrictors like SmFe2. In a composite magnetoelectric structure, this makes epitaxially-stabilized iron gallium a key material for energy-efficient beyond CMOS technologies. The energy dissipation and speed of magnetoelectric switching, however, is affected by the magnetic resonance frequency and damping. Here we report the evolution of the ferromagnetic resonance and key materials parameters (magnetic anisotropy, magnetic damping, and magnetostriction coefficient) for 70 nm thick epitaxially-stabilized single crystal A2 FeGa films beyond 19% Ga. Using flip chip ferromagnetic resonance (1-14 GHz), we find that the Gilbert damping parameter spans the range of 0.09-0.16 and decreases as the Ga concentration increases. This correlates an increasing magnetoelastic coupling with a reduction in the Gilbert damping. We find that the effective damping is a mix of contributions from the intrinsic magnon-phonon scattering and other scattering/dissipation mechanisms, with the latter being dominant especially at high Ga composition. Our results provide insight into the mechanism of magnetic relaxation in metastable high magnetostriction materials and potential switching behavior of composite magnetoelectrics.

cond-mat.mtrl-sci↗

arXiv2025

Perspective: Magnon-magnon coupling in hybrid magnonics

The internal coupling of magnetic excitations (magnons) with themselves has created a new research sub-field in hybrid magnonics, i.e., magnon-magnon coupling, which focuses on materials discovery and engineering for probing and controlling magnons in a coherent manner. This is enabled by, one, the abundant mechanisms of introducing magnetic interactions, with examples of exchange coupling, dipolar coupling, RKKY coupling, and DMI coupling, and two, the vast knowledge of how to control magnon band structure, including field and wavelength dependences of frequencies, for determining the degeneracy of magnon modes with different symmetries. In particular, we discuss how magnon-magnon coupling is implemented in various materials systems, with examples of magnetic bilayers, synthetic antiferromagnets, nanomagnetic arrays, layered van der Waals magnets, and (DMI SOT materials) in magnetic multilayers. We then introduce new concept of applications for these hybrid magnonic materials systems, with examples of frequency up/down conversion and magnon-exciton coupling, and discuss what properties are desired for achieving those applications.

cond-mat.mtrl-sci↗

arXiv2025

Magneto-optical spectroscopy based on pump-probe strobe light

We demonstrate a pump-probe strobe light spectroscopy for sensitive detection of magneto-optical dynamics in the context of hybrid magnonics. The technique uses a combinatorial microwave-optical pump-probe scheme, leveraging both the high-energy resolution of microwaves and the high-efficiency detection using optical photons. In contrast to conventional stroboscopy using a continuous-wave light, we apply microwave and optical pulses with varying pulse widths, and demonstrate magnetooptical detection of magnetization dynamics in Y3Fe5O12 films. The detected magneto-optical signals strongly depend on the characteristics of both the microwave and the optical pulses as well as their relative time delays. We show that good magneto-optical sensitivity and coherent stroboscopic character are maintained even at a microwave pump pulse of 1.5 ns and an optical probe pulse of 80 ps, under a 7 megahertz clock rate, corresponding to a pump-probe footprint of ~1% in one detection cycle. Our results show that time-dependent strobe light measurement of magnetization dynamics can be achieved in the gigahertz frequency range under a pump-probe detection scheme.

cond-mat.mes-hall↗

arXiv2025

Tuning Magneto-Optical Zero-Reflection via Dual-Channel Hybrid Magnonics

Multi-channel coupling in hybrid systems makes an attractive testbed not only because of the distinct advantages entailed in each constituent mode, but also the opportunity to leverage interference among the various excitation pathways. Here, via combined analytical calculation and experiment, we demonstrate that the phase of the magnetization precession at the interface of a coupled yttrium iron garnet(YIG)/permalloy(Py) bilayer is collectively controlled by the microwave photon field torque and the interlayer exchange torque, manifesting a coherent, dual-channel excitation scheme that effectively tunes the magneto-optic spectrum. The different torque contributions vary with frequency, external bias field, and types of interlayer coupling between YIG and Py, which further results in destructive or constructive interferences between the two excitation channels, and hence, selective suppression or amplification of the hybridized magnon modes.

cond-mat.mtrl-sci↗

arXiv2025

Theory of terahertz pulse transmission through ferroelectric nanomembranes

An analytical model is developed to predict the temporal evolution of the lattice polarization in ferroelectric nanomembranes upon the excitation by a terahertz (THz) electromagnetic pulse of an arbitrary waveform, and the concurrent transmission of the THz pulse in both the linear and the nonlinear regimes. It involves the use of the perturbation method to solve the equation of motion for the lattice polarization in both unclamped and strained ferroelectric nanomembranes within the framework of Landau-Ginzburg-Devonshire theory. The model is applicable to perovskite oxides such as BaTiO3 and SrTiO3, wurtzite Al1-xScxN, and trigonal LiNbO3. Our analytical model provides a theoretical basis for determining the thermodynamic and kinetic parameters of ferroelectric materials through THz transmission experiment. The calculation results also suggest an approach to reversing the chirality of a circularly polarized THz pulse by harnessing the resonant polarization-photon coupling in ferroelectrics. This capability of chirality reversal, along with the high tunability from a strain applied along any arbitrarily oriented in-plane axis, provides new opportunities for THz wave modulation without relying on complex metasurface designs.

cond-mat.mtrl-sci↗

arXiv2025

The Influence of Electric Field on the Anisotropic Dispersion of the Flexocoupling Induced Phonons and Ferrons in Van der Waals Ferrielectrics

As has been shown recently, the influence of the flexoelectric coupling (shortly "flexocoupling") on the fluctuations of electric polarization and elastic strains can lead to the principal changes of the dispersion law of soft optical and acoustic phonons (shortly "flexophonons") and ferrons (shortly "flexoferrons") in van der Waals ferrielectrics. Analytical results, derived in the framework of Landau-Ginzburg-Devonshire approach, revealed that the dispersion of flexophonons and flexoferrons is strongly anisotropic and should depend on the magnitude and direction of applied electric field. In this work we study the influence of applied electric field on the anisotropic dispersion of the flexophonons and flexophonons in a uniaxial van der Waals ferrielectric CuInP2S6. We reveal that the frequency of acoustic flexophonons and flexoferrons tends to zero at nonzero wavevectors under increase of applied electric field. We relate the changes with a possible appearance of a spatially modulated incommensurate polar phase induced by the flexocoupling in external field. The critical strength of flexocoupling is determined by the magnitude of electric field and direction of the wavevector. This allows us to propose a method for estimating the strength of flexocoupling in van der Waals ferrielectrics, providing that the frequency of the acoustic flexophonon is zeroing at the threshold value of the electric field. Since the flexoelectric coefficients are poorly known in van der Waals ferrielectrics, obtained analytical results can be useful for their flexo-engineering.

cond-mat.mtrl-sci↗

arXiv2025

Flexocoupling-induced phonons and ferrons in van der Waals ferroelectrics

The contribution of flexoelectric coupling to the long-range order parameter fluctuations in ferroics can be critically important to the ferron dispersion and related polar, pyroelectric and electrocaloric properties. Here we calculate analytically the dispersion relations of soft optic and acoustic flexocoupling-induced phonons and ferrons by incorporating the flexoelectric coupling, damping, and higher elastic gradients in the Landau-Ginzburg-Devonshire free energy functional using the van der Waals uniaxial ferrielectric CuInP2S6 as an example. We analyze the changes in the flexocoupling-induced phonon and ferron spectra arising from the appearance of spatially modulated phases induced by the flexoelectric coupling. We show that the free energy landscape of CuInP2S6 determines the specific features of its phonon spectra and ferron dispersion. We also discuss the contributions of optic and acoustic flexocoupling-induced ferrons to the pyroelectric and electrocaloric responses of CuInP2S6 at low temperatures.

cond-mat.mtrl-sci↗

arXiv2024

On-Demand Magnon Resonance Isolation in Cavity Magnonics

Cavity magnonics is a promising field focusing the interaction between spin waves (magnons) and other types of signals. In cavity magnonics, the function of isolating magnons from the cavity to allow signal storage and processing fully in the magnonic domain is highly desired, but its realization is often hindered by the lack of necessary tunability on the interaction. This work shows that by utilizing the collective mode of two YIG spheres and adopting Floquet engineering, magnonic signals can be switched on-demand to a magnon dark mode that is protected from the environment, enabling a variety of manipulation over the magnon dynamics. Our demonstration can be scaled up to systems with an array of magnonic resonators, paving the way for large-scale programmable hybrid magnonic circuits.

cond-mat.mes-hall↗

arXiv2024

Phase-resolving spin-wave microscopy using infrared strobe light

The needs for sensitively and reliably probing magnetization dynamics have been increasing in various contexts such as studying novel hybrid magnonic systems, in which the spin dynamics strongly and coherently couple to other excitations, including microwave photons, light photons, or phonons. Recent advances in quantum magnonics also highlight the need for employing magnon phase as quantum state variables, which is to be detected and mapped out with high precision in on-chip micro- and nano-scale magnonic devices. Here, we demonstrate a facile optical technique that can directly perform concurrent spectroscopic and imaging functionalities with spatial- and phase-resolutions, using infrared strobe light operating at 1550-nm wavelength. To showcase the methodology, we spectroscopically studied the phase-resolved spin dynamics in a bilayer of Permalloy and Y3Fe5O12 (YIG), and spatially imaged the backward volume spin wave modes of YIG in the dipolar spin wave regime. Using the strobe light probe, the detected precessional phase contrast can be directly used to construct the map of the spin wave wavefront, in the continuous-wave regime of spin-wave propagation and in the stationary state, without needing any optical reference path. By selecting the applied field, frequency, and detection phase, the spin wave images can be made sensitive to the precession amplitude and phase. Our results demonstrate that infrared optical strobe light can serve as a versatile platform for magneto-optical probing of magnetization dynamics, with potential implications in investigating hybrid magnonic systems.

cond-mat.mtrl-sci↗

arXiv2024

Dynamical phase-field model of cavity electromagnonic systems

Cavity electromagnonic system, which simultaneously consists of cavities for photons, magnons (quanta of spin waves), and acoustic phonons, provides an exciting platform to achieve coherent energy transduction among different physical systems down to single quantum level. Here we report a dynamical phase-field model that allows simulating the coupled dynamics of the electromagnetic waves, magnetization, and strain in 3D multiphase systems. As examples of application, we computationally demonstrate the excitation of hybrid magnon-photon modes (magnon polaritons), Floquet-induced magnonic Aulter-Townes splitting, dynamical energy exchange (Rabi oscillation) and relative phase control (Ramsey interference) between the two magnon polariton modes. The simulation results are consistent with analytical calculations based on Floquet Hamiltonian theory. Simulations are also performed to design a cavity electro-magno-mechanical system that enables the triple phonon-magnon-photon resonance, where the resonant excitation of a chiral, fundamental (n=1) transverse acoustic phonon mode by magnon polaritons is demonstrated. With the capability to predict coupling strength, dissipation rates, and temporal evolution of photon/magnon/phonon mode profiles using fundamental materials parameters as the inputs, the present dynamical phase-field model represents a valuable computational tool to guide the fabrication of the cavity electromagnonic system and the design of operating conditions for applications in quantum sensing, transduction, and communication.

cond-mat.mes-hall↗