Bulk Rashba spin splitting and Dirac surface state in $p$-type (Bi$_{0.9}$Sb$_{0.1})_2$Se$_3$ single crystal

TL;DR

This study reveals the coexistence of bulk Rashba spin splitting and Dirac surface states in p-type (Bi$_{0.9}$Sb$_{0.1})_2$Se$_3$ single crystals, driven by a structural transition, with implications for spintronics.

Contribution

It demonstrates the presence of bulk Rashba spin splitting and Dirac surface states in p-type (Bi$_{0.9}$Sb$_{0.1})_2$Se$_3$, supported by experimental and theoretical evidence, highlighting its potential for spintronic devices.

Findings

Bulk Rashba spin splitting observed below 30 K.

Dirac surface states confirmed by SdH oscillations.

Coexistence of orbital magnetism, bulk RSS, and surface states.

Abstract

We report bulk Rashba spin splitting (RSS) and associated Dirac surface state in (Bi$_{0.9}$Sb$_{0.1})_2$Se$_3$, exhibiting dominant $p$-type conductivity. We argue from the synchrotron diffraction studies that origin of the bulk RSS is due to a structural transition to a non-centrosymmetric $R3m$ phase below $\sim$ 30 K. The Shubnikov-de Haas Van (SdH) oscillations observed in the magnetoresistance curves at low temperature and the Landau level fan diagram, as obtained from these oscillations, confirm the presence of nontrivial Dirac surface state. The magnetization data at low temperature exhibit substantial orbital magnetization consistent with the bulk RSS. The existance of both the bulk RSS and Dirac surface states are confirmed by first principles density functional theory calculations. Coexistence of orbital magnetism, bulk RSS, and Dirac surface state is unique for $p$-type (Bi$_{0.9}$Sb$_{0.1})_2$Se$_3$, making it an ideal candidate for spintronic applications.