Symmetry-dependent antiferromagnetic proximity effects on valley splitting

Abstract

Various physical phenomena have been discovered by tuning degrees of freedom, among which there is the degree of freedom (DOF) -- "valley". The typical valley materials are characterized by two degenerate valley states protected by time-reversal symmetry (TS). These states indexed by valley DOF have been measured and manipulated for emergent valley-contrasting physics with the broken valley degeneracy. To achieve the valley splitting resulted from TS breaking, previous studies mainly focused on magnetic proximity effect provided by ferromagnetic (FM) layer. Nevertheless, the anti-ferromagnetic (AFM) proximity effect on the valley degeneracy has never been investigated systematically. In this work, we construct the composites consisting of a transitionmetal dichalcogenide (TMD) monolayer and a proximity layer with specific intra-plane AFM configurations. We extend the three-band model to describe the valley states of such systems. It is shown that either "time-reversal + fractional translation" or "mirror" symmetry has been proved to protect valley degeneracy. Additionally, first-principles calculations based on density functional theory (DFT) have been performed to verify the results obtained from the extended tight-binding (TB) model. The TB method introduced in the present work can properly describe the low-energy physics of valley materials that couple to the proximity with complex magnetic configurations. The results expand the range of qualified proximity layers for valley splitting, enabling more flexible manipulation of valley degree.

References in corpus (21)

• Atomically thin MoS2: A new direct-gap semiconductor
• Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides
• Van der Waals density functionals applied to solids
• Control of valley polarization in monolayer MoS2 by optical helicity
• Valley polarization in MoS2 monolayers by optical pumping
• MoS_2 as an ideal material for valleytronics: valley-selective circular dichroism and valley Hall effect
• Valley contrasting physics in graphene: magnetic moment and topological transport
• The Valley Hall Effect in MoS2 Transistors
• Valley Dependent Optoelectronics from Inversion Symmetry Breaking
• Three-band tight-binding model for monolayers of group-VIB transition metal dichalcogenides
• Magnetic Control of Valley Pseudospin in Monolayer WSe2
• Breaking of valley degeneracy by magnetic field in monolayer MoSe2
• Valley Splitting and Polarization by the Zeeman Effect in Monolayer MoSe2
• Electrical control of the valley Hall effect in bilayer MoS2 transistors
• Valley Manipulation by Optically Tuning the Magnetic Proximity Effect in WSe${}_2$/CrI${}_3$ Heterostructures
• Giant and tunable valley degeneracy splitting in MoTe2
• Unfolding first-principles band structures
• Observation of Magnetic Proximity Effect Using Resonant Optical Spectroscopy of an Electrically Tunable MoSe${}_2$/CrBr${}_3$ Heterostructure
• Systematic beyond-DFT study of binary transition metal oxides
• A general group theoretical method to unfold band structures and its application
• Two-dimensional topological superconducting phases emerged from d-wave superconductors in proximity to antiferromagnets