Emergence of Rashba spin valley state in two-dimensional strained bismuth oxychalcogenides Bi$_{2}$O$_{2}$Se

Muhammad Darwis Umar; Lalu Dalilul Falihin; Arief Lukmantoro; Harsojo; Moh. Adhib Ulil Absor

doi:10.1103/PhysRevB.108.035109

paper

Emergence of Rashba spin valley state in two-dimensional strained bismuth oxychalcogenides Bi $_{2}$ O $_{2}$ Se

arXiv:2304.10746 · doi:10.1103/PhysRevB.108.035109

Abstract

The experimental evidence of the ultra-high electron mobility and strong spin-orbit coupling in the two-dimensional (2D) layered bismuth-based oxyselenide, Bi $_{2}$ O $_{2}$ Se, makes it a potential material for spintronic devices. However, its spin-related properties have not been extensively studied due to the centrosymmetric nature of its crystal structure. By using first-principles density-functional theory calculation, this study reports the emergence of Rashba-spin-valley states in Bi $_{2}$ O $_{2}$ Se monolayer (ML). Breaking the crystal inversion symmetry of Bi $_{2}$ O $_{2}$ Se ML using an external electric field enables the Rashba-spin-valley formation, causing the appearance of the Rashba-type splitting around the $Γ$ valley and spin-valley coupling at the $D$ valleys located near the middle of $Γ - M$ line. In addition to the typical Rashba-type spin textures around the $Γ$ valley, the study also observed in-plane unidirectional spin textures around the $D$ valleys, which is a rare phenomenon in 2D materials. The observed Rashba-spin-valley states are driven by the lowering point group symmetry of the crystal from $D_{4 h}$ to $C_{4 v}$ enforced by the electric field, as clarified through $k \cdot p$ model derived from symmetry analysis. More importantly, tuning the Rashba and spin-valley states by using biaxial strain offers a promising route to regulate the spin textures and spin splitting preventing the electron from back-scattering in spin transport. Finally, we proposed a more realistic system, namely, Bi $_{2}$ O $_{2}$ Se ML/SrTiO $_{3}$ (001) heterointerface that supports the strong Rashba-spin-valley states and highlighting the potential of the Bi $_{2}$ O $_{2}$ Se ML for future spintronics and valleytronics-based devices.

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Emergence of Rashba spin valley state in two-dimensional strained bismuth oxychalcogenides Bi2​O2​Se

Abstract

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Emergence of Rashba spin valley state in two-dimensional strained bismuth oxychalcogenides Bi $_{2}$ O $_{2}$ Se