Cui

Quantum Anomalous Hall Effect in the Magnetic Topological Insulator Thin Films

10/23/2020

The quantum anomalous Hall (QAH) effect can be considered as the quantum Hall (QH) effect without an external magnetic field, which can be realized by time-reversal symmetry breaking in a topologically non-trivial system [1, 2]. A QAH system carries spin-polarized dissipationless chiral edge transport channels without the need for external energy input, hence may have a huge impact on future electronic and spintronic device applications for ultralow-power consumption. The many decades quest for the experimental realization of QAH phenomenon became a possibility in 2006 with the discovery of topological insulators (TIs). In 2013, the QAH effect was observed in thin films of Cr-doped TI for the first time [3]. Two years later in a near-ideal system, V-doped TI, contrary to the negative prediction from first principle calculations [2], a high-precision QAH quantization with more robust magnetization and a perfectly dissipationless chiral current flow was demonstrated [4]. In this talk, I will also talk about our recent progress on QAH sandwich heterostructures from the axion insulator physics [5] to the concurrence of the QAH and topological Hall effects [6] and the QAH-superconductor devices about the absence of evidence for chiral Majorana fermion excitations [7].