Concurrence of Quantum Anomalous Hall and Topological Hall Effects in Magnetic Topological Insulator Sandwich Heterostructures

TL;DR

This paper reports the experimental realization of coexistence of quantum anomalous Hall and topological Hall effects in magnetic topological insulator sandwich heterostructures, revealing entangled chiral edge states and spin textures.

Contribution

The study introduces a novel magnetic topological insulator sandwich structure that simultaneously exhibits QAH and TH effects, enabled by electric field gating and magnetic domain wall engineering.

Findings

Coexistence of QAH and TH effects demonstrated in heterostructures.

Chiral magnetic domain walls induced by gate-controlled Dzyaloshinskii-Moriya interaction.

Potential for dissipationless spintronic applications.

Abstract

The quantum anomalous Hall (QAH) effect is a quintessential consequence of non-zero Berry curvature in momentum-space. The QAH insulator harbors dissipation-free chiral edge states in the absence of an external magnetic field. On the other hand, the topological Hall (TH) effect, a transport hallmark of the chiral spin textures, is a consequence of real-space Berry curvature. While both the QAH and TH effects have been reported separately, their coexistence, a manifestation of entangled chiral edge states and chiral spin textures, has not been reported. Here, by inserting a TI layer between two magnetic TI layers to form a sandwich heterostructure, we realized a concurrence of the TH effect and the QAH effect through electric field gating. The TH effect is probed by bulk carriers, while the QAH effect is characterized by chiral edge states. The appearance of TH effect in the QAH insulating regime is the consequence of chiral magnetic domain walls that result from the gate-induced Dzyaloshinskii-Moriya interaction and occur during the magnetization reversal process in the magnetic TI sandwich samples. The coexistence of chiral edge states and chiral spin textures potentially provides a unique platform for proof-of-concept dissipationless spin-textured spintronic applications.