arXiv subjects

Jinyang Ni

Publications and source records attributed to Jinyang Ni.

12 recordsLinked to original sources

arXiv2026

Light-Driven Ferroic Switching Enables Reversible Control of Hydrogen Adsorption Thermodynamics

Reversible ultrafast switching of surface thermodynamics is highly desirable for hydrogen storage and catalysis yet remains elusive at the nanoscale. Here we demonstrate that photoinduced ferroic-order switching in two-dimensional ionic ferroelectric monolayers enables rapid, reversible control of hydrogen binding. In TiGeSe$_3$, carrier-density-driven redistribution of transition-metal 3\textit{d} orbital occupations triggers a sequential evolution from the ferroelectric ground state to paraelectric phases with staggered or Zig-Zag antiferromagnetic order. This switch continuously tunes the hydrogen adsorption free energy from 0.33 to 1.11 eV, shifting the interface from near-thermoneutrality to spontaneous desorption. Nonadiabatic dynamics indicate that electron-phonon coupling promotes nonthermal H release, while picosecond carrier recombination rapidly restores the initial ferroic order, closing an ultrafast reversible cycle. Generality is further validated in AgBiP$_2$Se$_6$ and CuInP$_2$S$_6$, establishing ferroic order as an optically addressable knob for dynamic thermodynamic reconfiguration beyond static design.

cond-mat.mtrl-sci↗

arXiv2026

Odd-Parity Chiral Magnons in Collinear Antiferromagnetic Multiferroics

Odd-parity magnetism represents an intriguing frontier in unconventional magnets; however, its realization has traditionally relied on noncollinear magnetic orders accompanied by broken spin conservation, which inevitably causes spin relaxation and dissipative transport of spin-encoded information. Here, we uncover a distinct route toward spin-conserving odd-parity magnon splitting enabled by antichiral Haldane-like flux (AHF) in collinear antiferromagnetic multiferroics. Symmetry analysis reveals that such AHF driven by intra-sublattice Dzyaloshinskii-Moriya interactions (DMI) gives rise to symmetry-dependent odd-parity magnon splittings, ranging from $p$-wave and $f$-wave to nodeless forms. Moreover, the coupling between ferroelectric modes and DMI provides an electric-field knob for manipulating chiral band splitting and magnon transport. Combining density functional theory (DFT) calculations, we identify a series of promising candidate materials in both 2D and bulk antiferromagnetic multiferroics. Our work provides new insights into the realization of odd-parity chiral magnons in collinear antiferromagnets and magnetoelectric coupling mechanisms in multiferroics.

cond-mat.mtrl-sci↗

arXiv2026

Electric-Switchable Chiral Magnons in PT-Symmetric Antiferromagnets

The magnons in antiferromagnetic insulators (AFIs) exhibit dual chirality, each carrying opposite spin angular momentum. However, in PT-symmetric AFIs, the magnon bands remain degenerate. In this work, we introduce a new class of PT-preserving AFIs in which the giant chiral splitting of magnons can be induced and controlled by an external electric field. Unlike conventional cases, such AFIs host a hidden dipole coupled to the antiferromagnetic order, which allows an external electric field to break the magnon sublattice symmetry and thereby largely lift the band degeneracy. Group theoretical analysis identifies the possible magnetic layer groups, while first-principles calculations and spin-wave theory reveal band splittings up to 20meV in Cr2CCl2 and Cr2CBr2 under the electric field of 0.2 V/{\AA}, corresponding to an effective magnetic field of 200T. In addition, the electrically controlled magnon chiral splitting enables reversible switching of magnon-mediated spin currents. These findings open a new route toward nonvolatile spintronics based on magnons.

cond-mat.mtrl-sci↗

arXiv2025

Electro-optic effects in some sliding ferroelectrics

Sliding ferroelectrics, which exhibit out-of-plane polarization arising from specific stacking rather than conventional ionic displacements, are new types of ferroelectrics whose underdeveloped physics needs to be explored. Here, we investigate the electro-optic (EO) response of these materials using first-principles calculations, focusing on ZrI$_{2}$ as a prototype. We reveal that, contrary to conventional ferroelectrics, the EO effect in ZrI$_{2}$ is dominated by its electronic contribution rather than the ionic one, which promises faster EO responses. Furthermore, both biaxial and uniaxial strains significantly enhance this response, and a universal-like linear relationship between the band gap and such response is discovered. We also report a large elasto-optic coefficient that is independent of biaxial strain. Similar large linear EO coefficients and properties are found in other sliding ferroelectrics, including different zirconium dihalides, as well as BN and BP bilayers. These findings highlight sliding ferroelectrics as highly promising candidates for ultrafast nonlinear optical devices and reveal unusual mechanisms.

cond-mat.mtrl-sci↗

arXiv2025

Nonreciprocal magnons in layered antiferromagnets VPX3(X =S,Se,Te)

Nonreciprocal magnons, characterized by propagation with differing energies along the k and -k directions, are crucial for modern spintronics applications. However, their realization in van der Waals layered antiferromagnets remains elusive. In this letter, we report robust nonreciprocal magnon behavior in layered honeycomb antiferromagnets VPX3(X =S,Se,Te). Our results demonstrate that, in addition to their intrinsic Dzyaloshinskii-Moriya interaction (DMI), the nonreciprocity of magnons is strongly influenced by the layer number, interlayer coupling, and magnon-magnon interactions. More importantly, in such layered antiferromagnets, the magnon nonreciprocity exhibits an asymmetric periodic dependence on the Neel vector, offering a novel route for experimentally probing antiferromagnetic order parameters in the 2D limit.

cond-mat.mtrl-sci↗

arXiv2025

Topological switching in bilayer magnons via electrical control

Topological magnons, quantized spin waves featuring nontrivial boundary modes, present a promising route toward lossless information processing. Realizing practical devices typically requires magnons excited in a controlled manner to enable precise manipulation of their topological phases and transport behaviors. However, their inherent charge neutrality and a high frequency nature pose a significant challenge for nonvolatile control, especially via electric means. Herein, we propose a general strategy for electrical control of topological magnons in bilayer ferromagnetic insulators. With strong spin-layer coupling, an applied vertical electric field induces an interlayer potential imbalance that modifies intralayer Heisenberg exchanges between adjacent layers. This electric-field-driven modulation competes with the bilayer's intrinsic Dzyaloshinskii-Moriya interaction, enabling the accurate tuning of the band topology and nonreciprocal dynamics of magnons. More importantly, such an electric control mechanism exhibits strong coupling with external magnetic fields, unveiling new perspectives on magnetoelectric coupling in charge-neutral quasiparticles

cond-mat.mes-hall↗

arXiv2025

Wavefunction-Free Approach for Predicting Nonlinear Responses in Weyl Semimetals

By sidestepping the intractable calculations of many-body wavefunctions, density functional theory (DFT) has revolutionized the prediction of ground states of materials. However, predicting nonlinear responses--critical for next-generation quantum devices--still relies heavily on explicit wavefunctions, limiting computational efficiency. In this letter, using the circular photogalvanic effect (CPGE) in Weyl semimetals as a representative example, we realize a 1000-fold computational speedup by eliminating the explicit dependence on wavefunctions. Our approach leverages the one-to-one correspondence between free parameters of Weyl fermions and the associated responses to obtain precise wavefunction-free formulations. Applying our methodology, we systematically investigated known Weyl semimetals and revealed that Ta$_3$S$_2$ exhibits photocurrents an order of magnitude greater than those observed in TaAs, with potential for an additional order-of-magnitude enhancement under strain. To further demonstrate the generality of our approach, we obtained a wavefunction-free formula for the Berry-curvature dipole in Weyl semimetals. Our work paves the way for substantially more efficient screening and optimization of nonlinear electromagnetic properties in topological quantum materials.

cond-mat.mtrl-sci↗

arXiv2025

Nonvolatile Magnonics in Bilayer Magnetic Insulators

Nonvolatile control of spin order or spin excitations offers a promising avenue for advancing spintronics; however, practical implementation remains challenging. In this letter, we propose a general framework to realize electrical control of magnons in 2D magnetic insulators. We demonstrate that in bilayer ferromagnetic insulators with strong spin-layer coupling, electric field Ez can effectively manipulate the spin exchange interactions between the layers, enabling nonvolatile control of the corresponding magnons. Notably, in this bilayer, Ez can induce nonzero Berry curvature and orbital moments of magnons, the chirality of which are coupled to the direction of Ez. This coupling facilitates Ez manipulate the corresponding magnon valley and orbital Hall currents. Furthermore, such bilayers can be easily engineered, as demonstrated by our density-functional-theory calculations on Janus bilayer Cr-based ferromagnets. Our work provides an important step toward realizing nonvolatile magnonics and paves a promising way for future magnetoelectric coupling devices.

cond-mat.mtrl-sci↗

arXiv2024

Interlayer Charge-density-wave Vector Phase Induced Structural Chirality

Chiral charge density waves (CDWs) have attracted intense interest due to their exotic quantum properties, yet the microscopic origin of structural chirality emerging from correlated charge order remains elusive. Here, we reveal that the interlayer phases of CDW wave vectors, an overlooked degree of freedom, play a crucial role in driving chiral structural displacements in layered CDW materials. By explicitly incorporating the interlayer phases in first-principles calculations, we successfully obtained the chiral structure of the CDW phases of AV$_3$Sb$_5$ (A= K, Rb, and Cs) and 1T-TiSe$_2$. The electronic and optical properties of the predicted chiral structures are consistent with experimental measurements of these materials in their CDW phases. We further predict that 1T-NbSe$_2$ is a promising material candidate for realizing chiral CDW order. Beyond materials prediction, our theory reveals that the chiral CDW can be manipulated by electron filling. Our study opens new avenues for discovering, designing, and engineering chiral CDW materials.

cond-mat.mtrl-sci↗

arXiv2024

Magnon Nonlinear Hall Effect in 2D Antiferromagnetic Insulators

The efficient detection of the magnetism in 2D antiferromagnetic (AFM) insulators is crucial for the advancement of 2D AFM spintronics and remains a challenging problem. In this letter, we introduce the magnon nonlinear Hall current, a second-order Hall response of collective spin excitations in ordered magnets, as a novel probe for 2D layered AFM insulators. We theoretically demonstrate that the nonlinear Hall effect is intrinsically coupled to the underlying spin configuration. In particular, it exhibits a pronounced layer dependence in layered antiferromagnets, enabling direct characterization of the nature and strength of interlayer magnetic coupling in multilayer AFM insulators. Furthermore, we show that a a slight external field perturbation can induce and manipulate the magnon nonlinear Hall response. Our work establishes a novel approach for exploring 2D antiferromagnetism and holds great promise for AFM spintronic applications

cond-mat.mes-hall↗

arXiv2024

Origin of zigzag antiferromagnetic orders in XPS3 (X= Fe, Ni) monolayers

Recently, two monolayer magnetic materials, i.e., FePS3 and NiPS3, have been successfully fabricated. Despite that they have the same atomic structure, the two monolayers exhibit distinct magnetic properties. FePS3 holds an out-of-plane zigzag antiferromagnetic (AFM-ZZ) structure, while NiPS3 exhibits an in-plane AFM-ZZ structure. However, there is no theoretical model which can properly describe its magnetic ground state due to the lack of a full understanding of its magnetic interactions. Here, by combining the first-principles calculations and the newly developed machine learning method, we construct an exact spin Hamiltonian of the two magnetic materials. Different from the previous studies which failed to fully consider the spin-orbit coupling effect, we find that the AFM-ZZ ground state in FePS3 is stabilized by competing ferromagnetic nearest-neighbor and antiferromagnetic third nearest-neighbor exchange interactions, and combining single-ion anisotropy. Whereas, the often ignored nearest-neighbor biquadratic exchange is responsible for the in-plane AFM-ZZ ground state in NiPS3. We additionally calculate spin-wave spectrum of AFM-ZZ structure in the two monolayers based on the exact spin Hamiltonian, which can be directly verified by the experimental investigation. Our work provides a theoretical framework for the origin of AFM-ZZ ground state in two-dimensional materials.

cond-mat.mtrl-sci↗

arXiv2021

Pressure-induced charge orders and their coupling to magnetism in hexagonal multiferroic LuFe2O4

Hexagonal LuFe2O4 is a promising charge-order (CO) driven multiferroic material with high charge and spin ordering temperatures. The coexisting charge and spin orders on Fe3+/Fe2+ sites result in novel magnetoelectric behaviors, but the coupling mechanism between the charge and spin orders remains elusive. Here, by tuning external pressure, we reveal three correlated spin-charge ordered phases in LuFe2O4: i) a centrosymmetric incommensurate three-dimensional CO with ferrimagnetism, ii) a non-centrosymmetric incommensurate quasi-two-dimensional CO with ferrimagnetism, and iii) a centrosymmetric commensurate CO with antiferromagnetism. Experimental in-situ single-crystal X-ray diffraction and X-ray magnetic circular dichroism measurements combined with density functional theory calculations suggest that the charge density redistribution caused by pressure-induced compression in the frustrated double-layer [Fe2O4] cluster is responsible for the correlated spin-charge phase transitions. The pressure-enhanced effective Coulomb interactions among Fe-Fe bonds drive the frustrated (1/3, 1/3) CO to a less frustrated (1/4, 1/4) CO, which induces the ferrimagnetic to antiferromagnetic transition. Our results not only elucidate the coupling mechanism among charge, spin and lattice degrees of freedom in LuFe2O4 but also provide a new way to tune the spin-charge orders in a highly controlled manner.

cond-mat.mtrl-sci↗