Quantum Anomalous Hall Multilayers Grown by Molecular Beam Epitaxy

Abstract

Quantum anomalous Hall (QAH) effect is a quantum Hall effect that occurs without the need of external magnetic field. A system composed of multiple parallel QAH layers is an effective high Chern number QAH insulator and the key to the applications of the dissipationless chiral edge channels in low energy consumption electronics. Such a QAH multilayer can also be engineered into other exotic topological phases such as a magnetic Weyl semimetal with only one pair of Weyl points. This work reports the first experimental realization of QAH multilayers in the superlattices composed of magnetically doped (Bi,Sb) 2 Te 3 topological insulator and CdSe normal insulator layers grown by molecular beam epitaxy. The obtained multilayer samples show quantized Hall resistance h/Ne 2 , where h is the Planck's constant, e is the elementary charge and N is the number of the magnetic topological insulator layers, resembling a high Chern number QAH insulator. Keywords quantum anomalous Hall effect, multilayer, molecular beam epitaxy, chiral edge state A quantum anomalous Hall (QAH) insulator (or Chern insulator) possesses topologically nontrivial band structure characterized by a non-zero Chern number (C). At each edge of a QAH insulator, there are C dissipationless chiral edge channels which give rise to quantized Hall resistance h/Ce 2 (h is

Tuning the Chern number in quantum anomalous Hall insulators

“…Since CdSe has the wurtzite structure, which is different from the tetradymite structure of magnetic TI, stacking faults inevitably arise in QAH/CdSe multilayer samples. These defects might be responsible for the reported large longitudinal resistance and the Hall resistances greater than the corresponding quantized values 26 .…”

MnBi2Te4-family intrinsic magnetic topological materials

“…2f, g) 17,18 . When Δ S and Δ D are both small compared with m, the TSSs are decoupled with each other, and the superlattice can be considered as many parallel and isolated QAH systems which is denoted by QAH multilayer (ML) 19 . The rich topological phases found in MnBi 2 Te 4 -family materials can be understood and engineered based on the phase diagrams.…”

Topological insulators-based magnetic heterostructures

“…Recently, by further optimizing the interfacial magnetic proximity effect, the quantum anomalous Hall effect with tunable Chern numbers has also been realized in the emergent MTI heterostructures [65][66][67]]. Following the concept of magnetic insulator with non-zero Chern number elaborated in Section 1, a novel FMI/TI/FMI sandwich heterostructure of (Zn,Cr)Te/(Bi,Sb) 2 Te 3 /(Zn,Cr)Te is grown by MBE, as illustrated in Figure 8a [66].…”