Proximity-Induced Magnetic Order in a Transferred Topological Insulator Thin Film on a Magnetic Insulator

Abstract

Breaking the time reversal symmetry (TRS) in a topological insulator (TI) by introducing a magnetic order gives rise to exotic quantum phenomena. One of the promising routes to inducing a magnetic order in a TI is utilizing magnetic proximity effect between a TI and a strong magnetic insulator (MI). In this article, we demonstrate a TI/MI heterostructure prepared through transferring a molecular beam epitaxy (MBE)-grown BiSe film onto a yttrium iron garnet (YIG) substrate via wet transfer. The transferred BiSe exhibits excellent quality over a large scale. Moreover, through wet transfer we are able to engineer the interface and perform a comparative study to probe the proximity coupling between BiSe and YIG under different interface conditions. A detailed investigation of both the anomalous Hall effect and quantum corrections to the conductivity in magnetotransport measurements reveals an induced magnetic order as well as TRS breaking in the transferred BiSe film on YIG. In contrast, a thin layer of AlO at the interface obstructs the proximity coupling and preserves the TRS, indicating the critical role of the interface in mediating magnetic proximity effect.

Record High-Proximity-Induced Anomalous Hall Effect in (BixSb1–x)2Te3 Thin Film Grown on CrGeTe3 Substrate

“…In order to probe the AHE signal, we performed the Hall measurement on two BST (6 QL)/CGT samples with different carrier types (one p-and the other n-type, denoted as Sample P and Sample N respectively), as shown in Figure 3 for Sample P and 145 Ω for Sample N, more than one order larger than the RAH values reported in previous works. [16][17][18]21 Absence of hysteresis in RAH is due to softness of the ferromagnetism and is consistent with the magnetization data ( Figure 1(d)) of the CGT substrate. 24…”

“…It is also notable that a recent work reported that CGT flake imprints its magnetization in the AHE of Pt thin film deposited on top, 32 Figure 4. [16][17][18]21 From Figure 4, we can see that the BST/CGT system is significantly better than previous proximity systems, based on both and tan values. The and tan achieved in Sample P (N) are 153 Ω (145 Ω) and 0.01286 (0.00715), respectively, more than one order larger than previous proximity-coupled systems.…”

Observation of Quantum Anomalous Hall Effect and Exchange Interaction in Topological Insulator/Antiferromagnet Heterostructure

“…Experimentally, high-quality Cr 2 O 3 can be readily grown on the Al 2 O 3 (0001) via either sputtering, pulsed laser deposition, or molecular beam epitaxy (MBE), as the two materials have similar lattice constants and the same crystal symmetry. [12][13][14] Given our previous experience of the Cr:(Bi,Sb) 2 Te 3 growth on the Al 2 O 3 (0001) substrate, [15] the realization of a QAH insulator on Cr 2 O 3 is thus feasible. Furthermore, Cr 2 O 3 is a magnetoelectric material in which a net magnetic moment can be induced by applying an electric field.…”

Strongly Surface State Carrier‐Dependent Spin–Orbit Torque in Magnetic Topological Insulators

“…A small exchange gap is opened in the TSS because of the magnetic dopant that breaks time‐reversal symmetry in the Cr‐BST layer. [ 27,28 ] If the Fermi circle of the TSS in the k ‐space is shifted by a DC current along the x ‐axis, the spin‐momentum locking will lead to a spin accumulation transverse to the x ‐direction. The bilayer film was then fabricated into devices with Hall bar geometry by photolithography for magneto‐transport and optical measurements (Figure 1c).…”