【直播】【人大物理学系】Prof. Kam Tuen Law: Giant magneto-electric effect...

In recent years, interacting, topological and superconducting phases have been discovered in atomically thin two-dimensional materials such as in transition metal dichalcogenides (TMDs) and 2D moiré materials. In this talk, I would like to discuss:

1. The current-induced magnetization switching in twisted bilayer graphene. Recently, quantum anomalous Hall effect with spontaneous ferromagnetism was observed in twisted bilayer graphenes (TBG) near ¾ filling by Goldhaber-Gordon’s group at Stanford and Young’s group at UCSB. Importantly, it was observed that an extremely small current can switch the direction of the magnetization. This offers the prospect of realizing low energy dissipation magnetic memories.  However, the mechanism of the current-driven magnetization switching is poorly understood as the charge currents in graphene are generally believed to be non-magnetic. In this talk, the observed current-induced magnetization effect will be explained.

2. The properties of superconducting, topological, monolayer 1T’-WTe₂.

Experimentally, 1T’-WTe₂ is a centrosymmetric superconductor with upper critical field several times larger than the Pauli limit. We explained that the enhanced upper critical field is due to the so-called spin-orbit-parity coupling which is important for materials with topological band inversion.