Giant longitudinal negative magneto-resistance under perpendicular magnetic field in Bi$_{2-x}$Fe$_x$Se$_{3-x}$S$_x$ Topological insulators

TL;DR

This study reveals giant negative magneto-resistance in Fe and S co-doped Bi2Se3 topological insulators, persisting at room temperature, linked to ferromagnetic ordering and the destruction of non-trivial bulk states at high doping levels.

Contribution

It demonstrates the emergence of giant negative MR in doped Bi2Se3 and connects it to magnetic ordering and topological state degradation, providing insights into tuning topological insulator properties.

Findings

Giant negative MR observed at specific doping levels

Negative MR persists up to room temperature

High doping destroys non-trivial bulk states

Abstract

The magnetic, magneto-transport and ARPES studies of Fe and S co-doped Bi2Se3 were investigated. With doping concentration magneto-resistance (MR) gradually decreases and for a certain doping concentration giant negative MR is observed which persists up to room temperature. Magnetic measurement indicates that the negative MR is observed when ferromagnetic ordering is induced with Fe doping. The magnetic ordering can be attributed with the RKKY interaction. Positive MR reappears with larger doping concentration which may be attributed to the decrease of FM ordering due to the turning off of the spin-orbit coupling leading to the destruction of non-trivial bulk state. This in-effect de-hybridizes the conduction band with the Fe spin. The ARPES data also indicates that above a critical doping concentration (x>0.09) the non-trivial bulk state is completely destroyed.