Interface-induced sign reversal of the anomalous Hall effect in magnetic topological insulator heterostructures

Abstract

The Berry phase picture provides important insights into the electronic properties of condensed matter systems. The intrinsic anomalous Hall (AH) effect can be understood as the consequence of non-zero Berry curvature in momentum space. Here, we fabricate TI/magnetic TI heterostructures and find that the sign of the AH effect in the magnetic TI layer can be changed from being positive to negative with increasing the thickness of the top TI layer. Our first-principles calculations show that the built-in electric fields at the TI/magnetic TI interface influence the band structure of the magnetic TI layer, and thus lead to a reconstruction of the Berry curvature in the heterostructure samples. Based on the interface-induced AH effect with a negative sign in TI/V-doped TI bilayer structures, we create an artificial “topological Hall effect”-like feature in the Hall trace of the V-doped TI/TI/Cr-doped TI sandwich heterostructures. Our study provides a new route to create the Berry curvature change in magnetic topological materials that may lead to potential technological applications.

Quantum Oscillations in Ferromagnetic (Sb, V)2Te3 Topological Insulator Thin Films

“…This shift is accompanied by a reduction of the period, that is, a growth in F, which indicates a dramatic temperature-dependent change of the band structure in the doped sample, thereby confirming the findings of a recent report. [42] Nevertheless, the origin thereof remains unclear. One possibility is that a small gap separates the Fermi level and the V-3d impurity states.…”

Quantum anomalous Hall edge channels survive up to the Curie temperature

“…As the Hall resistance takes on values clearly below h / e 2 (where h is Planck’s constant and e the elementary charge) at temperatures above 1 K or so, well below T C , where the bulk remains robustly ferromagnetic, the nonquantized Hall resistance can in principle originate from the ordinary bulk states in the absence of any chiral edge channel. Moreover, the possible presence of two distinct ferromagnetic phases 14 and the otherwise rich magnetic behavior reported at low temperature 10 , 13 , 18 – 21 leave open the possibility of a second phase transition being involved, and thus possibly playing a role in the edge channel formation at some temperature below T C .…”

2D Bi2Se3 materials for optoelectronics

“…The dark current of the heterostructure was obviously suppressed, but the responsivity still has room for improvement because of the weak optical absorption that originates from its atomically thin nature. In view of this, Zhai and co-authors constructed a hybrid heterostructure by integrating metal-organic frameworks (MOFs) nanoparticles with strong optical absorption on the surface of 2D Bi 2 Se 3 flakes ( Figure 5 D) ( Wang et al., 2021a , 2021b , 2021c , 2021d ). In this case, the MOF nanoparticles can not only serve as a photosensitive material to absorb incident light, but also act as a photogate layer to regulate the channel conductance of Bi 2 Se 3 channel ( Figure 5 E), thereby enhancing the photoconductivity gain of the device and realizing high-performance photodetection.…”

“…Compared with their bulk counterparts, 2D layered materials usually show unique features because of quantum confinement effect along the vertical direction of the 2D plane ( Akinwande et al., 2014 ; Liu et al., 2020a , 2020b , 2020c ; Ricciardulli et al., 2021 ). Atomically smooth surfaces without dangling bonds enable them to be compatible with any 2D materials and mature complementary metal oxide semiconductor (CMOS) process without considering lattice matching ( Akinwande et al., 2019 ; Iannaccone et al., 2018 ; Liang et al., 2019 ; Liu et al., 2019a , 2019b ; Wang et al., 2021a , 2021b , 2021c , 2021d ). Moreover, the electronic band structures of 2D layered materials cover a wide range of electromagnetic spectrum, meaning that diverse optical and electrical properties reside in their family ( Liu et al., 2021a , 2021b ; Xia et al., 2014 ).…”

“…In the last decade, a wealth of 2D layered materials have been isolated from bulk crystals or been fabricated through bottom-up synthesis ( Cai et al., 2018 ; Fang et al., 2021 ; Han et al., 2019a , 2019b ; Li et al., 2017 ; Varoon et al., 2011 ; Wang et al., 2020a , 2020b ; Zhou et al., 2018 ). Their fundamental physical properties and demonstrative functional devices have been thoroughly studied ( Koppens et al., 2014 ; Sierra et al., 2021 ; Wang et al., 2019a , 2019b , 2019c , 2021a , 2021b , 2021c , 2021d )). These thereby vastly promote the application of 2D layered materials in next-generation advanced devices.…”