Probing the Interaction Between Topological and Rashba-like Surface States in MnBi$_2$Te$_4$ Through Sn Doping

TL;DR

This study explores how Sn doping in MnBi2Te4 influences Rashba-like surface states, revealing their energy shift, hybridization with topological states, and potential for tuning electronic properties for spintronics.

Contribution

It provides a detailed analysis of the interaction between topological and Rashba-like surface states in Mn-Sn doped Bi2Te4 using DFT and ARPES, highlighting tunability of surface states.

Findings

Sn doping shifts Rashba-like surface states downward in energy.

Rashba-like states hybridize with topological surface states.

Rashba states are localized within the first three Te-Bi-Te trilayers.

Abstract

The presence of Rashba-like surface states (RSS) in the electronic structure of topological insulators (TIs) has been a longstanding topic of interest due to their significant impact on electronic and spin structures. In this study, we investigate the interaction between topological and Rashba-like surface states (TSS and RSS) in Mn$_{1-x}$Sn$_x$Bi$_2$Te$_4$ systems using density functional theory (DFT) calculations and high-resolution ARPES. Our findings reveal that increasing Sn concentration shifts RSS downward in energy, enhancing their influence on the electronic structure near the Fermi level. ARPES validates these predictions, capturing the evolution of RSS and their hybridization with TSS. Orbital analysis shows RSS are localized within the first three Te-Bi-Te trilayers, dominated by Bi $p$-orbitals, with evidence of the orbital Rashba effect enhancing spin-momentum locking. At higher Sn concentrations, RSS penetrate deeper into the crystal, driven by Sn $p$-orbital contributions. These results position Mn$_{1-x}$Sn$_x$Bi$_2$Te$_4$ as a tunable platform for tailoring electronic properties in spintronic and quantum technologies.