Valleytronics Candidate with Spontaneous Valley Polarization in A-Type Antiferromagnetic MoSi₂N₄/MnPS₃ Heterostructure

Abstract

Two-dimensional (2D) antiferromagnetic (AFM) heterostructures (HTSs) have broad application prospects since they offer a stray-free field, robustness against magnetic perturbations, and faster spin dynamics, but how to effectively control valley polarization with an AFM substrate is still an issue. Here spin−valley physical coupling in monolayers of MoSi 2 N 4 and AFM MnPS 3 is due to spin−orbit coupling and the absence of inversion symmetry, which made broad application prospects of spin and valley in novel 2D materials. Spontaneous valley polarization in MoSi 2 N 4 /MnPS 3 HTS has been confirmed by using the first-principles calculations and low-energy effective Hamiltonian models. We reveal that its Neél temperature calculated by Monte Carlo simulation is about 340 K above room temperature, which is higher than many 2D AFM materials. The magnetic proximity phenomenon caused by interfacial orbital hybridization is gradually strengthened thanks to the reduction of the distance between the two layers, and valley splitting of the MoSi 2 N 4 /MnPS 3 HTS is calculated to be Δ K−K′ = 9.15 meV. Our computational results offer a basis for the valley polarization in an intrinsic AFM HTS and a practical approach to design and utilize valleytronics devices.

Controllable dual-polarization valley physics in the strain-engineered 2D monolayer of VC2N4

“…3,4 The advancements in valleytronics have primarily focused on the utilization of time-reversal-connected valleys, where valley polarization is dynamically or statically induced through external methods. 5–13 For example, it is well known that strain, 14,15 magnetic proximity effect, 16–19 and optical pumping 20,21 can be used to tune the energies of valleys. However, these methods suffer from various problems, such as a short lifetime of carriers, impurity scattering, and low efficiency.…”

Enhancement and modulation of valley polarization in Janus CrSSe with internal and external electric fields

“…Graphene is the first promising 2D material for valley polarization. 9,10 However, its semi-metallic nature hinders its integration into valleytronics devices. Unlike graphene, some new valley materials with band gaps have been proposed, such as MoS 2 , 11–13 SnS, 9,14 MoSi 2 N 4 , and TcIrGe 2 S 6 .…”

“…In recent years, several methods for generating valley polarization have been proposed, including optical pumping, 29–31 breaking the crystal symmetry, 32 applied magnetic fields, 33,34 magnetic atom doping, 35,36 and the magnetic proximity effect. 10,11,13,37–43 Among them, the magnetic proximity effect is a particularly effective and accessible method for introducing large valley polarization in valley-polarized materials. For instance, the magnetic proximity effect of ferromagnetic substrates, such as Fe 3 GeTe 2 , 11 MnPS 3 , 10 yttrium iron garnet, 43 ScI 2 , 42 CoO, and MnO, 44,45 induces large valley polarization.…”

“…10,11,13,37–43 Among them, the magnetic proximity effect is a particularly effective and accessible method for introducing large valley polarization in valley-polarized materials. For instance, the magnetic proximity effect of ferromagnetic substrates, such as Fe 3 GeTe 2 , 11 MnPS 3 , 10 yttrium iron garnet, 43 ScI 2 , 42 CoO, and MnO, 44,45 induces large valley polarization.…”

Gate-field control of valley polarization in valleytronics

“…These heterostructures generally not only maintain the valley DoF of the original monolayers, but also can have unique and required properties by design. [36][37][38][39][40][41][42][43][44][45] On the other hand, the physics in 2D systems are more abundant than that in 1D systems. Therefore, it is the discovery and the experimental detection of the 2D valleytronic materials, graphene and transitional metal dichalcogenides (TMDs), that make the field of valleytronics undergo rapid development in the past decade.…”