Current-induced switching of proximity-induced ferromagnetic surface states in a topological insulator

Masataka Mogi,Kei S Takahashi,Reika Fujimura,Masashi Kawasaki,Kenji Yasuda,Atsushi Tsukazaki,Minoru Kawamura,Yoshinori Tokura,Ryutaro Yoshimi,Naoki Ogawa

doi:10.1038/s41467-021-21672-9

Abstract

Electrical manipulation of magnetization could be an essential function for energy-efficient spintronics technology. A magnetic topological insulator, possessing a magnetically gapped surface state with spin-polarized electrons, not only exhibits exotic topological phases relevant to the quantum anomalous Hall state but also enables the electrical control of its magnetic state at the surface. Here, we demonstrate efficient current-induced switching of the surface ferromagnetism in hetero-bilayers consisting of the topological insulator (Bi1-xSbx)2Te3 and the ferromagnetic insulator Cr2Ge2Te6, where the proximity-induced ferromagnetic surface states play two roles: efficient charge-to-spin current conversion and emergence of large anomalous Hall effect. The sign reversal of the surface ferromagnetic states with current injection is clearly observed, accompanying the nearly full magnetization reversal in the adjacent insulating Cr2Ge2Te6 layer of an optimal thickness range. The present results may facilitate an electrical control of dissipationless topological-current circuits.

Highlights

Electrical manipulation of magnetization could be an essential function for energy-efficient spintronics technology
The spin accumulation may enable the electrical manipulation of the topological insulators (TIs) surface ferromagnetism that originates from the FM proximity coupling at the FM-layer/TI
The layered FM insulator (FMI) compound of CGT23,24 has recently been found to provide strong proximity coupling with the TI surface state, as exemplified by the observation of large anomalous Hall effect (AHE) originating from a prominent Berry curvature near the exchange gap formed in the proximity-coupled surface state[25] (Fig. 1b)

Summary

Introduction

Electrical manipulation of magnetization could be an essential function for energy-efficient spintronics technology. Since the efficient spin transfer to the FMI layer requires strong couplings with wellordered interfaces between the TI surface state and the magnetic moments in the FMI layer[26,27], the CGT/TI heterostructures may be of great advantage for highly efficient switching.

Results

Conclusion