Enhancing the Quantum Anomalous Hall Effect by Magnetic Codoping in a Topological Insulator

Abstract

The quantum anomalous Hall (QAH) effect, which has been realized in magnetic topological insulators (TIs), is the key to applications of dissipationless quantum Hall edge states in electronic devices. However, investigations and utilizations of the QAH effect are limited by the ultralow temperatures needed to reach full quantization-usually below 100 mK in either Cr- or V-doped (Bi,Sb) Te of the two experimentally confirmed QAH materials. Here it is shown that by codoping Cr and V magnetic elements in (Bi,Sb) Te TI, the temperature of the QAH effect can be significantly increased such that full quantization is achieved at 300 mK, and zero-field Hall resistance of 0.97 h/e is observed at 1.5 K. A systematic transport study of the codoped (Bi,Sb) Te films with varied Cr/V ratios reveals that magnetic codoping improves the homogeneity of ferromagnetism and modulates the surface band structure. This work demonstrates magnetic codoping to be an effective strategy for achieving high-temperature QAH effect in TIs.

Magnetic-impurity-induced modifications to ultrafast carrier dynamics in the ferromagnetic topological insulators Sb2−xVxTe3

“…Furthermore, in the host TIs (Sb 1−x Bi x ) 2 Te 3 , the carrier type can be widely tuned from p to n with an increase of x [21][22][23]. Especially, V-doped (Sb,Bi) 2 Te 3 is a hard ferromagnet exhibiting a larger coercive field and higher Curie temperature compared to the Cr-doped cases but the working temperature of the QAHE is still very low although extensive efforts have been made to improve it by modulation doping or co-doping methods [24,25].…”

Chiral Hall effect in the kink states in topological insulators with magnetic domain walls

“…The anomalous Hall effect (AHE) exits in the absence of external magnetic field, and appears due to internal magnetisation. [28][29][30][31][32][33][34][35] Such effect can also be found in two dimensional hexagonal lattices [36,37], closely related to the models we consider here. Recent experiments have reported large AHE in topological insulators with proximity induced magnetism.…”

Hinged quantum spin Hall effect in antiferromagnetic topological insulators

“…Moreover, the magnetically doped (Bi,Sb) 2 Te 3 TI and CdSe normal insulator layers in the superlattice structure has been successfully grown by molecular beam epitaxy [33]. It has been shown that the coercive field of magnetic TI in each layer can be controlled by mixing the dopants Cr and V at varied ratios [66]. In fact, a magnetic TI bilayer with different dopants ratios was driven to the opposite magnetization by sweeping the magnetic field in a recent experiment [67].…”