Interface effects on the magnetic-proximity-induced quantized Hall response in heterostructures based on three-dimensional topological insulators

Abstract

We report a theoretical study of the spin-dependent transport properties in heterostructures containing a three-dimensional topological insulator (TI) thin film and ferromagnetic normal insulator (FMNI) slab. Within the framework of a continual approach for the FMNI/TI/FMNI trilayer model, we reveal how the magnetic proximity effect at the TI/FMNI interface can influence an intrinsic Hall response of the system. We predict that the FMNI/TI/FMNI trilayer undergoes a transition into the quantum anomalous Hall phase either from the topologically trivial phase or from the quantum spin Hall phase, which is controlled by tuning the proximity-induced exchange field, the TI film thickness, and the TI band structure parameters. We draw the corresponding phase diagram of the FMNI/TI/FMNI trilayer. Moreover, we argue that the roughness at the TI/FMNI interfaces can cause the decomposition of the TI film into topologically distinct domains, which affects the Hall conductivity. We discuss the specifics of manifestation and complexities of observation of quantized conductivity in realistic TI/FMNI heterostructures.

Recent Progress in Proximity Coupling of Magnetism to Topological Insulators

“…Theoretical studies have shown that when a TI is sandwiched between two FMI, it can undergo a transition into the quantum anomalous Hall phase either from the topologically trivial phase or from the quantum spin Hall phase as a function of film thickness and strength of magnetic exchange. [ 212 ] Hou et al. have discussed the realization of QAHE at high temperature through DFT calculations for a van der Waals ferromagnet monolayer—CrI 3 interfaced with Bi 2 Se 3 , [ 42 ] and more detailed calculations predicted that when a Bi 2 Se 3 film with thickness of 5 QL or more is sandwiched between two CrI 3 layers, it becomes a QAHI due to the competition between the exchange field from CrI 3 and interaction of the top and bottom surfaces of Bi 2 Se 3 film.…”

Absence of Magnetic Proximity Effect at the Interface of Bi2Se3 and (

“…However, our data does not show evidence of such an intercalation. Other interfacial effects, including charge transfer at the TI/MI interface and band bending could explain the absence of induced magnetism in the TI and the lack of observation of the QAHE [51][52][53][54][55]. Another possibility for the absence of proximity effects would be the presence of a magnetic dead layer at the TI/EuS interface.…”

Spectral features of magnetic domain walls on surface of 3D topological insulators

“…The disagreement between some spectroscopic probes indicating a relatively large exchange gap at the TI surface and the low temperature range of the QAHE realization remains an important matter [68]. The quantized conductivity effects in real systems are affected by a complex network of topologically non-trivial and trivial conducting channels running along boundaries, separating regions of distinct topological phases [69]. Our results demonstrate the presence of the DW-induced states embodying the conducting channels at the magnetic surface of TI and describe their characteristics.…”