Field-effect Modulation of Anomalous Hall Effect in Diluted Ferromagnetic Topological Insulator Epitaxial Films

TL;DR

This study demonstrates that Cr-doped Sb2Te3 topological insulator films exhibit carrier-independent ferromagnetism and a tunable anomalous Hall effect, highlighting their potential for quantum anomalous Hall and spintronic applications.

Contribution

It reveals that Cr doping does not affect Dirac surface states and introduces carrier-independent ferromagnetism in Sb2Te3 films, with implications for quantum Hall effects.

Findings

Dirac surface states are insensitive to Cr doping

Robust long-range ferromagnetic order is achieved

Anomalous Hall effect can be modulated by gating

Abstract

High quality chromium (Cr) doped three-dimensional topological insulator (TI) Sb2Te3 films are grown via molecular beam epitaxy on heat-treated insulating SrTiO3(111) substrates. We report that the Dirac surface states are insensitive to Cr doping, and a perfect robust long-range ferromagnetic order is unveiled in epitaxial Sb2-xCrxTe3 films. The anomalous Hall effect is modulated by applying a bottom gate, contrary to the ferromagnetism in conventional diluted magnetic semiconductors (DMSs), here the coercivity field is not significantly changed with decreasing carrier density. Carrier-independent ferromagnetism heralds Sb2-xCrxTe3 films as the base candidate TI material to realize the quantum anomalous Hall (QAH) effect. These results also indicate the potential of controlling anomalous Hall voltage in future TI-based magneto-electronics and spintronics.