Proximity Induced High-Temperature Magnetic Order in Topological Insulator - Ferrimagnetic Insulator Heterostructure

TLDR

Introducing magnetic order in a topological insulator breaks time‑reversal symmetry of its surface states, enabling novel physics and spintronic applications, yet such effects have only been observed at temperatures far below practical levels. This study investigates the magnetic properties of Bi₂Se₃ surface states when placed in proximity to the high‑Tc ferrimagnetic insulator yttrium iron garnet. The authors examine proximity‑induced magnetism by measuring magnetoresistance loops under out‑of‑plane and in‑plane fields and by magneto‑optical Kerr effect on Bi₂Se₃/YIG heterostructures. They observe butterfly and square‑shaped magnetoresistance loops correlated with YIG magnetization and detect a magnetic signal from Bi₂Se₃ up to 130 K, demonstrating proximity‑induced TI magnetism at elevated temperatures toward room‑temperature spintronics.

Abstract

Introducing magnetic order in a topological insulator (TI) breaks time-reversal symmetry of the surface states and can thus yield a variety of interesting physics and promises for novel spintronic devices. To date, however, magnetic effects in TIs have been demonstrated only at temperatures far below those needed for practical applications. In this work, we study the magnetic properties of Bi2Se3 surface states (SS) in the proximity of a high Tc ferrimagnetic insulator (FMI), yttrium iron garnet (YIG or Y3Fe5O12). Proximity-induced butterfly and square-shaped magnetoresistance loops are observed by magneto-transport measurements with out-of-plane and in-plane fields, respectively, and can be correlated with the magnetization of the YIG substrate. More importantly, a magnetic signal from the Bi2Se3 up to 130 K is clearly observed by magneto-optical Kerr effect measurements. Our results demonstrate the proximity-induced TI magnetism at higher temperatures, an important step toward room-temperature application of TI-based spintronic devices.