Magnetic quantum phase transition in Cr-doped Bi2(SexTe1-x)3 driven by the Stark effect

TL;DR

This paper demonstrates that an external electric field can induce a magnetic phase transition in Cr-doped Bi2(SexTe1-x)3 topological insulators near the quantum critical point, via the Stark effect, enabling electrical control of magnetic and topological states.

Contribution

It reveals that gate electric fields can control magnetic phases in topological insulators through the Stark effect near the quantum critical point, advancing topological spintronic device potential.

Findings

Gate voltage affects magnetic order only near the QCP.

Electric field induces a topological quantum phase transition.

Electrical control of magnetic and topological properties demonstrated.

Abstract

The interplay between magnetism and topology, as exemplified in the magnetic skyrmion systems, has emerged as a rich playground for finding novel quantum phenomena and applications in future information technology. Magnetic topological insulators (TI) have attracted much recent attention, especially after the experimental realization of quantum anomalous Hall effect. Future applications of magnetic TI hinge on the accurate manipulation of magnetism and topology by external perturbations, preferably with a gate electric field. In this work, we investigate the magneto transport properties of Cr doped Bi2(SexTe1-x)3 TI across the topological quantum critical point (QCP). We find that the external gate voltage has negligible effect on the magnetic order for samples far away from the topological QCP. But for the sample near the QCP, we observe a ferromagnetic (FM) to paramagnetic (PM) phase transition driven by the gate electric field. Theoretical calculations show that a perpendicular electric field causes a shift of electronic energy levels due to the Stark effect, which induces a topological quantum phase transition and consequently a magnetic phase transition. The in situ electrical control of the topological and magnetic properties of TI shed important new lights on future topological electronic or spintronic device applications.