Observation of a Highly Spin Polarized Topological Surface State in GeBi$_{2}$Te$_{4}$

TL;DR

This study demonstrates that GeBi$_{2}$Te$_{4}$ exhibits a highly spin-polarized topological surface state with over 75% polarization near the Dirac point, promising for spintronic applications.

Contribution

It provides the first detailed spin polarization measurement of GeBi$_{2}$Te$_{4}$'s topological surface state, showing robustness against disorder.

Findings

Spin polarization exceeds 75% near the Dirac point.

Disorder has minor effect on surface state spin polarization.

Potential for enhanced spintronic and thermoelectric functionalities.

Abstract

Spin polarization of a topological surface state for GeBi$_2$Te$_4$, the newly discovered three-dimensional topological insulator, has been studied by means of the state of the art spin- and angle-resolved photoemission spectroscopy. It has been revealed that the disorder in the crystal has a minor effect on the surface state spin polarization and it exceeds 75% near the Dirac point in the bulk energy gap region ($\sim$180 meV). This new finding for GeBi$_{2}$Te$_{4}$ promises not only to realize a highly spin polarized surface isolated transport but to add new functionality to its thermoelectric and thermomagnetic properties.