Symmetry-Breaking Phenomena in MnPS3/TMDC Heterostructures: Non-relativistic Spin Splitting, Altermagnetism and Spin-Valley Effects

TL;DR

This work analyzes symmetry-breaking phenomena in MnPS$_3$/TMDC heterostructures to reveal how stacking geometry and magnetic order govern nonrelativistic spin splitting, altermagnetism, and spin-valley coupling. Using first-principles DFT with a Hubbard $U$ of $1.8$ eV, the authors examine two high-symmetry stackings, S1 and S2, and quantify interlayer registry, strain effects, and magnetic interactions through an extended spin Hamiltonian. They identify two NRSS regimes: altermagnetic-like band crossings in S2 and symmetry-breaking NRSS in S1, with NRSS tunable by interfacial registry; SOC induces a conduction-valley splitting $ riangle^{CB}$ that is controllable via the MnPS$_3$ spin orientation. The findings establish MnPS$_3$ as a symmetry-tunable antiferromagnetic substrate that can induce and manipulate spin and valley phenomena in 2D heterostructures without requiring net magnetization or strong SOC, offering routes toward nonvolatile valleytronic and opto-spintronic devices.

Abstract

We explore symmetry-breaking phenomena in MnPS3/TMDC (MoS2, WS2, MoSe2, WSe2) heterostructures using first-principles calculations, considering two high-symmetry stacking configurations, S1 and S2, which differ not only by their interfacial registry but also by a 30° twist between the layers. Depending on the stacking geometry, the systems exhibit two distinct types of nonrelativistic spin splitting (NRSS): S2 hosts altermagnetic-like band crossings, while S1 shows global spin splitting characteristic of symmetry-breaking NRSS. Magnetic exchange and anisotropy parameters indicate that the intrinsic magnetic properties of MnPS3 are largely preserved upon interfacing. Including spin-orbit coupling, we find tunable conduction-valley splitting controlled by the MnPS3 spin orientation. Our results identify MnPS3 as a symmetry-tunable antiferromagnetic substrate capable of inducing and controlling spin and valley effects in 2D heterostructures without relying on net magnetization or strong SOC, offering a route toward nonvolatile valleytronic functionalities.

Figures (6)

• Figure 1: Interlayer potential energy surface (PES) for the representative system of MnPS$_3$/MoS$_2$. Top and side views of (a) pristine TMT (MnPS3) layer, (b) TMDC MX2 (M = Mo, W and X = S, Se) layer. In each case, rigid in-plane shift of the MnPS$_3$ relative to the TMDC layer are performed along the crystallographic x and y directions, quantified by a relative displacement parameter $\delta$. The PES is defined as $\Delta E(\delta)= (E(\delta)-E(\delta=0))/A_{hBL}$, where $A_{hBL}$ is the surface area of heterobilayer. All scans are rigid lateral translations at fixed interlayer spacing, where no in-plane or out-of-plane atomic relaxations are allowed-so the PES is registry-dependent interlayer potential. Schematic representations of the translation paths are presented at the bottom of (c) and (d) panels, whereas the right side of these panels show the reference stackings S1 ($\delta=0$) and S2 ($\delta=0$), for which the minima of PES occur.
• Figure 2: Heisenberg exchange parameters ($|J_1|$) in meV and MnPS$_3$ strain ($\varepsilon_{MnPS_3}$) in percent for MnPS$_3$/TMDC heterostructures (S1) in various stacking configurations.
• Figure 3: (a) Band edge positions (VBM and CBM) respect to the vacuum level for the employed MnPS$_3$/TMDC heterostructures. Results are shown for two stacking configurations (S1 and S2) as well as for pristine, non-interacting monolayers ("P"), all calculated independently for each system. (b) Electronic band structure of the MoSe$_2$/MnPS$_3$ heterostructure in the S1 stacking configuration with orbital projections onto the constituent layers (MoSe$_2$ – blue, MnPS$_3$ – red). On the right, the real part of the pseudo-wavefunction (rWF) is visualized for the conduction band minimum (CBM) and valence band maximum (VBM). (c) Band structure and corresponding rWF plots for the same heterostructure in the S2 stacking configuration, showing the spatial character of the CBM and VBM states.
• Figure 4: Non-relativistic spin splitting (NRSS) and stacking-dependent magnetic effects in MnPS$_3$/TMDC heterostructures. Stacking S2 (shown on the left side of the figure) exhibits symmetry-paired AFM behavior- visualization (a), whereas stacking S1 corresponds to a symmetry-breaking AFM configuration -(f). (b) Schematic illustration of spin band structures showing two types of antiferromagnetic (AFM) states: symmetry-paired AFMs, characteristic of altermagnetism with opposite spin bands crossing, and (g) symmetry-breaking AFMs. Electronic structure for (c) stacking configuration S2: Spin-unresolved band structure of MnPS$_3$/MoSe$_2$ highlighting the Mn 3d$^5$ contributions; (d) Zoomed-in spin-resolved bands (spin up: blue, spin down: red) along the K$^+$M/2–$\Gamma$–K$^-$M/2 path showing clear altermagnetic splitting; (e) Average altermagnetic splitting ⟨AS⟩ as a function of in-plane layer translation ($\delta$) for x- and y-shifts. Analogous results for stacking configuration S1: (h) Spin-unresolved band structure with Mn 3d$^5$ contributions; (i) Spin-resolved zoom-in revealing NRSS-type splitting without typical spin up/down inversion; (j) ⟨AS⟩ dependence on stacking translation, showing distinct behavior from the altermagnetic S2 configuration.
• Figure 5: Conduction band valley splitting ($\Delta^{CB}$) in various heterostructures as a function of the spin orientation. Band structures of the MnPS$_3$/MoSe$_2$ in the S1 stacking configuration with Mn spins aligned (a) in-plane and (b) out-of-plane. A conduction band valley splitting ($\Delta^{CB}$) is observed for the out-of-plane spin orientation. The top panels show schematic illustrations of the in-plane and out-of-plane spin orientations. (c) Comparison of valley splitting $\Delta^{CB}$ for all studied TMDC/MnPS$_3$ heterostructures and for pristine MnPS$_3$, in both stacking configurations S1 and S2.