arXiv subjects

San-Dong Guo

Publications and source records attributed to San-Dong Guo.

At least 19 recordsLinked to original sources

arXiv2026

Robust $d$-wave altermagnetism in $\mathrm{XCr_2Y_2O}$ (X=K, Rb, Cs; Y=S, Se, Te) family

The $\mathrm{KV_2Se_2O}$, $\mathrm{Rb_{1-δ}V_2Te_2O}$ and $\mathrm{Cs_{1-δ}V_2Te_2O}$ are experimentally confirmed to adopt either C-type or G-type antiferromagnetic configuration, corresponding to apparent or hidden altermagnetism. However, their nearly degenerate energies lead to inconsistent experimental assignments between the two antiferromagnetic configurations. Here, we predict that the experimentally synthesized $\mathrm{RbCr_2Se_2O}$ is a robust $d$-wave altermagnetic metal, since the energy difference between C-type and G-type configurations is large, which is independent of electron correlation strength and van der Waals interaction. Upon applying in-plane uniaxial strain, $\mathrm{RbCr_2Se_2O}$ can generate a net total magnetic moment via a direct piezomagnetic effect, which is distinct from semiconductor that typically requires carrier doping in addition to strain. This provides an experimental strategy for distinguishing the G-type antiferromagnetic configuration, in which the total magnetic moment remains zero under uniaxial strain. Our work presents an isostructural $d$-wave altermagnetic $\mathrm{RbCr_2Se_2O}$ analogous to $\mathrm{KV_2Se_2O}$, $\mathrm{Rb_{1-δ}V_2Te_2O}$ and $\mathrm{Cs_{1-δ}V_2Te_2O}$, which can facilitate further experimental verification. Furthermore, these results are universal across materials of this family $\mathrm{XCr_2Y_2O}$ (X=K, Rb, Cs; Y=S, Se, Te), thus expanding the family of altermagnets.

cond-mat.mtrl-sci↗

arXiv2026

Zero-net-magnetization hybrid magnet

Zero-net-magnetization magnets possess ultradense and ultrafast application potential, benefiting from their intrinsic zero stray field and terahertz dynamics characteristics. Herein, we propose the concept of zero-net-magnetization hybrid magnet, in which magnetic atoms with opposite spin polarization are partially coupled via spatial inversion ($P$) symmetry, partially via rotation/mirror ($C/M$) symmetry or partially without any symmetry correlation. From a local perspective and neglecting the interactions between local regions, hybrid magnet can be regarded as being composed of $PT$-antiferromagnet (possessing the combined symmetry ($PT$) of $P$ and time-reversal ($T$)), altermagnet, or fully compensated ferrimagnet. To realize hybrid magnet, we propose that such system can be constructed by forming heterojunction with three types of zero-net-magnetization magnetic monolayers. We mainly investigate the heterojunction composed of two kinds of zero-net-magnetization magnets, among which one type corresponds to fully compensated ferrimagnet. When heterojunction hybrid magnet exhibits a type-II band alignment, only one of electron doping and hole doping can induce a net magnetic moment, while the other hardly generates any net magnetization. Taking the heterojunction constructed by $PT$-antiferromagnet and fully compensated ferrimagnet as an example, we verify our proposal by means of the tight-binding (TB) model. Finally, taking the $\mathrm{Cr_2C_2S_6}$/$\mathrm{CrMoC_2S_6}$ heterojunction as an example, we perform first-principles calculations combined with electric field modulation to validate our TB model and theoretical proposal.

cond-mat.mtrl-sci↗

arXiv2026

Reversible fully spin polarization in strain-engineered two-dimensional fully compensated magnets

Achieving controllable spin polarization and its reversal in symmetry-compensated magnets. Here we demonstrate, using symmetry analysis and a minimal tight-binding model, that uniaxial strain removes these constraints by inducing inequivalence between magnetic sublattices in two-dimensional (2D) system, driving an altermagnetic (AM) state into a fully compensated ferrimagnetic (fFIM) state and enabling fully spin polarization. Furthermore, strain along orthogonal directions gives rise to two energetically degenerate fFIM states with opposite spin polarization, enabling reversible spin switching. More importantly, the two symmetry-related fFIM states can be regarded as distinct ferroelastic variants, suggesting that this model or mechanism can be extended to ferroelastic fFIM systems. The generality of this mechanism is confirmed by combining spin-group analysis, first-principles calculations, and Boltzmann transport theory in representative candidates, including AM Mn$_2$SeO and ferroelastic fFIM V$_2$SO. Our results reveal a universal symmetry-driven framework for strain-controlled and -reversible fully spin-polarized transport and identify strain-engineered AM and ferroelastic fFIM systems as a promising platform for volatile and nonvolatile spintronic applications.

cond-mat.mtrl-sci↗

arXiv2026

Distinguishing apparent and hidden altermagnetism via uniaxial strain in $\mathrm{CsV_2Te_2O}$-family

The hidden altermagnetism has been theoretically proposed and then experimentally confirmed in metal $\mathrm{Cs_{1-δ}V_2Te_2O}$, which exhibits two nearly degenerate ground-state magnetic configurations (C-type and G-type) corresponding respectively to apparent and hidden altermagnetism. Here, we propose that in-plane uniaxial strain can be utilized to distinguish apparent and hidden altermagnetism. Under uniaxial strain, apparent altermagnetism exhibits an obvious net magnetic moment, whereas hidden altermagnetism maintains zero net magnetic moment. The magnetic moment induced by uniaxial strain here, namely the piezomagnetic effect, differs from that in semiconductors, where strain must be applied first followed by carrier doping to generate net magnetism. First-principles calculations verify our proposal, revealing that the magnetic moment induced by uniaxial strain in C-type antiferromagnetic $\mathrm{CsV_2Te_2O}$ is much larger than that in the previously studied altermagnetic semiconductors. Furthermore, we also investigate the electronic state transitions of semiconductors featuring a crystal structure analogous to $\mathrm{CsV_2Te_2O}$ under uniaxial strain, and verify our proposal in specific material via first-principles calculations. Our work provides an experimentally feasible strategy to distinguish apparent and hidden altermagnetism in material $\mathrm{Cs_{1-δ}V_2Te_2O}$, and extends the physical implication of the piezomagnetic effect, which can be directly verified in experimentally synthesizable $\mathrm{KV_2Se_2O}$ and $\mathrm{Rb_{1-δ}V_2Te_2O}$.

cond-mat.mtrl-sci↗

arXiv2026

Hidden half-metallicity

Half-metals, featuring ideal 100\% spin polarization, are widely regarded as key materials for spintronic and quantum technologies; however, the half-metallic state is intrinsically fragile, as it relies on a delicate balance of exchange splitting and band filling and is therefore highly susceptible to disorder, external perturbations, and thermal effects. Here we introduce the concept of hidden half-metallicity, whereby the global electronic structure of a symmetry-enforced net-zero-magnetization magnet is non-half-metallic, while each of its two symmetry-related sectors is individually half-metallic, enabling robust 100\% spin polarization through a layer degree of freedom. Crucially, the vanishing net magnetization of the entire system suppresses stray fields and magnetic instabilities, rendering the half-metallic functionality inherently more robust than in conventional ferromagnetic half-metals. Using first-principles calculations, we demonstrate this mechanism in a $PT$-symmetric bilayer $\mathrm{CrS_2}$, and further show that an external electric field drives the system into a seemingly forbidden fully compensated ferrimagnetic metal in which hidden half-metallicity persists. Finally, we briefly confirm the realization of hidden half-metallicity in altermagnets, establishing a general paradigm for stabilizing half-metallic behavior by embedding it in symmetry-protected hidden sectors and opening a new route toward the design and discovery of unprecedented half-metallic phases.

cond-mat.mtrl-sci↗

arXiv2025

External-field-induced transition from altermagnetic metal to fully-compensated ferrimagnetic metal in monolayer $\mathrm{Cr_2O}$

Altermagnets and fully-compensated ferrimagnets are two canonical classes of zero-net-moment magnets. An altermagnetic (AM) half-metal cannot exist due to its AM spin splitting, while a fully-compensated ferrimagnetic (FC-FIM) metal seems impossible to realize because both spin channels remain gapless. Here, we propose that an FC-FIM metal can be realized by breaking the rotational or mirror symmetry that links two spin-opposite magnetic atoms in an AM metal. We further demonstrate that charge-carrier doping is fundamentally unable to generate a net magnetic moment in an altermagnet, whereas such a net moment can be readily induced in a fully-compensated ferrimagnet. We use the AM monolayer $\mathrm{Cr_2O}$ as a concrete example to validate our proposal. Either electric field or uniaxial strain can break the $S_{4z}$ symmetry of $\mathrm{Cr_2O}$, thereby inducing a transition from an AM metal to an FC-FIM metal. Uniaxial strain plus carrier doping creates a net moment in an altermagnet, and the so-called piezomagnetism is essentially a strain-driven switch from altermagnetism to fully-compensated ferrimagnetism. By analogy, we advance the concept of electromagnetism: an electric field drives the transition from altermagnetism to fully-compensated ferrimagnetism, and subsequent charge-carrier doping stabilizes a net magnetization. Our work provides a roadmap for further exploring the connection and distinction between altermagnet and fully-compensated ferrimagnet, and confirms the feasibility of FC-FIM metal.

cond-mat.mtrl-sci↗

arXiv2025

A route to fully-compensated ferrimagnetic metal: electric-field annihilation of the bilayer bandgap

Fully-compensated ferrimagnet has garnered widespread attention due to its zero-net total magnetic moment and non-relativistic global spin splitting. In general, for a fully-compensated ferrimagnet, at least one spin channel should be gapped to ensure a zero-net total magnetic moment, which would lead to a fully-compensated ferrimagnetic (FC-FIM) semiconductor or half-metal, and appears to limit the existence of an FC-FIM metal. Here we propose that an FC-FIM metal can be achieved by electrically closing the gap of a bilayer system. Using two-dimensional (2D) ferromagnetic (FM) semiconductor as building block, we examine both FM and antiferromagnetic (AFM) interlayer couplings and distinguish unipolar magnetic semiconductor (UMS) and bipolar magnetic semiconductor (BMS) monolayers. It is concluded that an electric field can annihilate the bilayer gap and realize the FC-FIM metal only when the interlayer coupling is AFM and the building block is a UMS. Our scheme for realizing an FC-FIM metal can be generalized to electrically tuned 2D spin-degenerate metal with spin-layer locking. Using first-principles calculations, we have validated our proposal by taking bilayer MnOF, bilayer $\mathrm{ScI_2}$ and monolayer $\mathrm{Hf_2S}$ as examples. Our work offers an alternative route to realize the originally forbidden FC-FIM metal, paving the way for further exploration of FC-FIM metal.

cond-mat.mtrl-sci↗

arXiv2025

Achieving fully-compensated ferrimagnetism through two-dimensional heterojunctions

In addition to altermagnets, fully-compensated ferrimagnets are another category of collinear magnetic materials that possess zero-net total magnetic moment and exhibit spin-splitting, making them promising for low-energy spintronics, high-density data storage and high-sensitivity sensors. Although many methods, such as alloying, external electric field, Janus engineering, ferroelectric field and spin ordering, have been proposed to achieve fully-compensated ferrimagnetism, these approaches either face experimental difficulties or produce a small spin-splitting or are volatile. Here, we propose to form vertical heterostructures by stacking two different but equally magnetized two-dimensional ferromagnetic materials. If an A-type antiferromagnetic ordering is satisfied, a fully compensated ferrimagnet can be formed. This vertical heterostructure approach is insensitive to lattice matching and stacking manner, thus being more conducive to experimental realization. Through first-principles calculations, we verify our proposal with several examples, focusing in particular on $\mathrm{CrI_3}$/$\mathrm{CrGeTe_3}$ heterojunction composed of experimentally synthesized $\mathrm{CrI_3}$ and $\mathrm{CrGeTe_3}$ monolayers. The calculations show that $\mathrm{CrI_3}$/$\mathrm{CrGeTe_3}$ is a fully-compensated ferrimagnet, with pronounced spin-splitting, and that tensile strain is more favorable for achieving fully-compensated ferrimagnetism. Our work provides an experimentally feasible strategy for realizing fully-compensated ferrimagnetism, thereby further advancing the development of this field.

cond-mat.mtrl-sci↗

arXiv2025

Hidden fully-compensated ferrimagnetism

Incorporating zero-net-magnetization magnets that exhibit spin-splitting into spintronics delivers key advantages: faster switching dynamics, greater immunity to destabilizing fields, lower power consumption, and markedly improved overall efficiency. The collinear magnets with net-zero magnetization and spin-splitting mainly include altermagnet and fully-compensated ferrimagnet, which provide possibility to achieve hidden spin polarization (HSP) with net-zero spin polarization in total but non-zero local spin polarization. In addition to proposal of hidden altermagnetism, we hereby introduce this concept of hidden fully-compensated ferrimagnetism, where the total spin polarization is zero, but either of the two inversion-partner sectors possesses fully-compensated ferrimagnetism with non-zero local spin polarization in the real space. By the first-principle calculations, we predict that $PT$-bilayer $\mathrm{CrMoC_2S_6}$ is a possible hidden fully-compensated ferrimagnet, showing fully-compensated ferrimagnetic HSP, which can be separated and observed by an out-of-plane external electric field. Our works provide a class of hidden spin-polarized materials that facilitates the advancement of spintronics.

cond-mat.mtrl-sci↗

arXiv2025

Spin ordering-induced fully-compensated ferrimagnetism

Fully-compensated ferrimagnets exhibit zero net magnetic moment yet display non-relativistic global spin splitting, making them highly advantageous for constructing high-performance spintronic devices. The general strategy is to break the inversion symmetry of conventional antiferromagnets or the rotational/mirror symmetry of altermagnets to achieve fully-compensated ferrimagnets. Here, we propose to induce fully-compensated ferrimagnetism by engineering the spin ordering rather than modifying the lattice structure. Bilayer stacking engineering offers a convenient platform to verify our proposal and readily enables switching between two distinct electronic states by tuning the $\mathrm{N\acute{e}el}$ vector of one layer. By the first-principles calculations, a bilayer system is constructed with monolayer $\mathrm{Cr_2C_2S_6}$ as the elementary building block to corroborate our proposal. This strategy can also be extended to inducing altermagnetism via spin ordering engineering. Our work offers an alternative route to realize non-relativistic spin splitting in zero-net-magnetization magnets, paving the way for the advancement and construction of low-power spintronic device.

cond-mat.mtrl-sci↗

arXiv2025

Weak valley-layer coupling and valley polarization in centrosymmetric $\mathrm{FeCl_2}$ monolayer

Using the valley degree of freedom as a carrier of information for storage and processing, valley polarization plays a crucial role. A variety of mechanisms for valley polarization have been proposed, among which the valley-layer coupling mechanism involves the induction of valley polarization by an out-of-plane electric field. Here, through first-principles calculations, it is found that the weak valley-layer coupling can exist in centrosymmetric $\mathrm{FeCl_2}$ monolayer. It is crucial to note that valley-layer coupling only occurs with out-of-plane magnetization and vanishes with in-plane magnetization. Compared to monolayers with strong valley-layer coupling, $\mathrm{FeCl_2}$ requires an extremely strong electric field to achieve the same magnitude of valley splitting. Valley polarization switching can be achieved by manipulating the directions of magnetization and electric field. Reversing only one of these directions switches the valley polarization, whereas reversing both simultaneously leaves it unchanged. Moreover, the simply stacked bilayer $\mathrm{FeCl_2}$, as a $PT$-antiferromagnet, can spontaneously achieve valley polarization without an external electric field, highlighting its potential for miniaturization, ultradensity, and ultrafast performance. Our work provides guidelines for identifying materials with weak valley-layer coupling, and further enables the regulation of valley polarization through electric field and stacking engineering.

cond-mat.mtrl-sci↗

arXiv2025

External-field-induced altermagnetism in experimentally synthesized monolayer $\mathrm{CrX_3}$ (X=Cl, Br and I)

Net-zero-magnetization magnets are attracting significant research interest, driven by their potential for ultrahigh density and ultrafast performance. Among these materials, the altermagnets possess alternating spin-splitting band structures and exhibit a range of phenomena previously thought to be exclusive to ferromagnets, including the anomalous Hall and Nernst effects, non-relativistic spin-polarized currents, and the magneto-optical Kerr effect. Bulk altermagnets have been experimentally identified, while two-dimensional (2D) altermagnets remain experimentally unexplored. Here, we take experimentally synthesized 2D ferromagnetic $\mathrm{CrX_3}$ (X=Cl, Br and I) as the parent material and achieve altermagnetism through external field. First, we achieve the transition from ferromagnetism to antiferromagnetism through biaxial strain. Subsequently, we break the space inversion symmetry while preserving the mirror symmetry via an electric field, thereby inducing altermagnetism. Moreover, through the application of Janus engineering to construct $\mathrm{CrX_{1.5}Y_{1.5}}$ (X$\neq$Y=Cl, Br and I), the phase transition from ferromagnetism to antiferromagnetism induced by strain alone is sufficient to trigger the emergence of altermagnetism. All six monolayers possess the symmetry of $i$-wave spin-splitting. The computational results suggest that $\mathrm{CrCl_3}$ can be readily tuned to exhibit altermagnetism through external field in experiment, thanks to its low strain threshold for magnetic phase transition. Our work provides experimentally viable materials and methods for realizing altermagnetism, which can advance the development of 2D altermagnetism.

cond-mat.mtrl-sci↗

arXiv2025

Electric-field-induced fully-compensated ferrimagnetism in experimentally synthesized monolayer MnSe

Owing to their inherent characteristics of zero stray field and terahertz dynamics, two-dimensional (2D) zero-net-magnetization magnets demonstrate the potential for miniaturization, ultradensity and ultrafast performance. Recently, fully-compensated ferrimagnet of 2D zero-net-magnetization magnets has already attracted attention, as it can exhibit global spin-splitting, magneto-optical response and anomalous Hall effect [\textcolor[rgb]{0.00,0.00,1.00}{Phys. Rev. Lett. 134, 116703 (2025)}]. Therefore, it is very important to provide experimentally feasible strategies and materials to achieve fully-compensated ferrimagnets. Here, we use the experimentally synthesized A-type $PT$-antiferromagnet (the joint symmetry ($PT$) of space inversion symmetry ($P$) and time-reversal symmetry ($T$)) MnSe as the parent material to induce fully-compensated ferrimagnetism through an out-of-plane electric field. This electric field can remove the $P$ symmetry of the lattice, thereby breaking the $PT$ symmetry and inducing spin-splitting. When considering spin-orbital coupling (SOC), MnSe with an out-of-plane magnetization can achieve the anomalous valley Hall effect (AVHE). In addition, we also discuss inducing fully-compensated ferromagnetism via Se vacancies and Janus engineering. Our works can promote the further development of 2D fully-compensated ferrimagnets both theoretically and experimentally.

cond-mat.mtrl-sci↗

arXiv2025

Two-dimensional fully-compensated Ferrimagnetism

Antiferromagnetic spintronics has long been a subject of intense research interest, and the recent introduction of altermagnetism has further ignited enthusiasm in the field. However, fully-compensated ferrimagnetism, which exhibits band spin splitting but zero net magnetization, has yet to receive enough attention. Since the experimental preparation of two-dimensional (2D) magnetic van der Waals (vdW) materials in 2017, 2D magnetic materials, thanks to their super tunability, have quickly become an important playground for spintronics. Here, we extend the concept of fully-compensated ferrimagnetism (fFIM) to two dimensions and propose 2D \textit{filling-enforced} fFIM, demonstrate its stability and ease of manipulation, and present three feasible realization schemes with respective exemplary candidate materials. A simple model for 2D fully-compensated ferrimagnets (fFIMs) is developed. Further investigation of 2D fFIMs' physical properties reveals that they not only exhibit significant magneto-optical response but also show fully spin-polarized currents and the anomalous Hall effect in the half-metallic states, displaying characteristics previously almost exclusive to ferromagnetic materials, greatly broadening the research and application prospects of spintronic materials.

cond-mat.mtrl-sci↗

arXiv2025

Symmetry-breaking induced transition among net-zero-magnetization magnets

Net-zero-magnetization magnets have garnered intensive research attention due to their ultradense and ultrafast potential. In terms of the symmetric classification of connecting magnetic atoms with opposite spin polarization, the net-zero-magnetization magnets mainly include $PT$-antiferromagnet (the joint symmetry ($PT$) of space inversion symmetry ($P$) and time-reversal symmetry ($T$)), altermagnet and fully-compensated ferrimagnet. Studying transitions among net-zero-magnetization magnets is essentially the research on symmetry breaking, which can also clearly reveal the transformation of spin-splitting symmetry. Symmetry breaking can be achieved through methods such as Janus engineering, isovalent alloying, and external electric field. Here, we start from a parent $PT$-antiferromagnet that simultaneously possesses both $P$ and rotational/mirror symmetries to induce altermagnet and fully-compensated ferrimagnet. Based on first-principles calculations, the proposed transitions can be verified in $PT$-antiferromagnet $\mathrm{CrC_2S_6}$ monolayer. By Janus engineering and isovalent alloying, $\mathrm{CrC_2S_6}$ can change into altermagnetic $\mathrm{CrC_2S_3Se_3}$ and fully-compensated ferrimagnetic $\mathrm{CrMoC_2S_6}$. The $\mathrm{CrC_2S_3Se_3}$ can also become fully-compensated ferrimagnetic $\mathrm{CrMoC_2S_3Se_3}$ by isovalent alloying. Our work provides a clear and intuitive example to explain the transitions among net-zero-magnetization magnets, which can inspire more research on net-zero-magnetization magnets.

cond-mat.mtrl-sci↗

arXiv2024

Hidden altermagnetism

Hidden spin polarization (HSP) with zero net spin polarization in total but non-zero local spin polarization has been proposed in certain nonmagnetic centrosymmetric compounds, where the individual sectors forming the inversion partners are all inversion asymmetry. Here, we extend this idea to antiferromagnetic materials with $PT$ symmetry (the joint symmetry of space inversion symmetry ($P$) and time-reversal symmetry ($T$)), producing zero net spin polarization in total, but either of the two inversion-partner sectors possesses altermagnetism, giving rise to non-zero local spin polarization in the real space, dubbed "hidden altermagnetism". By first-principle calculations, we predict that $PT$-symmetric bilayer $\mathrm{Cr_2SO}$ can serve as a possible candidate showing altermagnetic HSP. By applying an external electric field to break the global $P$ symmetry, the hidden altermagnetism can be separated and observed experimentally. Our works extend the hidden physics, and will also advance the theoretical and experimental search for new type of spin-polarized materials.

cond-mat.mtrl-sci↗

arXiv2024

Multifield tunable valley splitting and anomalous valley Hall effect in two-dimensional antiferromagnetic MnBr

Compared to the ferromagnetic materials that realize the anomalous valley Hall effect by breaking time-reversal symmetry and spin-orbit coupling, the antiferromagnetic materials with the joint spatial inversion and time-reversal (PT) symmetry are rarely reported that achieve the anomalous valley Hall effect. Here, we predict that the antiferromagnetic monolayer MnBr possesses spontaneous valley polarization. The valley splitting of valence band maximum is 21.55 meV at K and K' points, which is originated from Mn-dx2-y2 orbital by analyzing the effective Hamiltonian. Importantly, monolayer MnBr has zero Berry curvature in the entire momentum space but non-zero spin-layer locked Berry curvature, which offers the condition for the anomalous valley Hall effect. In addition, the magnitude of valley splitting can be signally tuned by the onsite correlation, strain, magnetization rotation, electric field, and built-in electric field. The electric field and built-in electric field induce spin splitting due to breaking the P symmetry. Therefore, the spin-layer locked anomalous valley Hall effect can be observed in MnBr. More remarkably, the ferroelectric substrate Sc2CO2 can tune monolayer MnBr to realize the transition from metal to valley polarization semiconductor. Our findings not only extend the implementation of the anomalous valley Hall effect, but also provides a platform for designing low-power and non-volatile valleytronics devices.

cond-mat.mtrl-sci↗

arXiv2024

Proposal of a general scheme: valley polarization in antiferromagnetic bilayer systems

Superior to ferromagnetic (FM) valleytronics, antiferromagnetic (AFM) counterpart exhibits ultradense and ultrafast potential due to their intrinsic advantages of zero stray field, terahertz dynamics, and compensated moment of antiferromagnets. However, the physics of spontaneous valley polarization is mainly rooted in FM hexagonal lattices and is rarely used to explore the simultaneous spin and valley polarizations in AFM materials. Here, we propose a general stacking way to achieve valley polarization in AFM bilayer systems. The hexagonal ferrovalley material is used as the basic building unit, and then the space-inversion centrosymmetric bilayer system with interlayer AFM ordering is constructed by horizontal mirror and 2-fold rotational operations, which can exhibit spontaneous valley polarization. In this construction process, the rarely explored \textit{layer-locked hidden valley polarization}, hidden Berry curvature and layer Hall effect are involved, and an out-of-plane electric field can be used to detect hidden valley polarization and to realize layer-locked anomalous valley Hall effect. We use three examples to illustrate our proposal. Firstly, the Janus GdBrI is used to prove concepts and effects involved in our design process. Secondly, the $\mathrm{RuBr_2}$ is used to demonstrate other phenomena, including valley polarization transition and \textit{near-ideal quantum spin Hall insulator}. Finally, we use our design principles to understand the valley polarization of experimentally synthesized MnSe from a new perspective. Our works establish a robust general scheme to achieve valley polarization in AFM bilayer systems, thereby opening up new avenues for AFM valleytronics.

cond-mat.mtrl-sci↗