Atsushi Tsukazaki1

1, Institute for Materials Research, Tohoku University, Sendai, , Japan

Quantm anomalous Hall effect in magnetic topological insulator (TI) heterostructures has attracted much attention for demonstrating an edge current conduction at zero magnetic field [1-3]. Magnetic topological insulator contains spontaneous magnetization along z-direction that interacts with surface states, resulting in a formation of exchange gap in the surface states. When Fermi energy locates in the exchange gap at low temperature, longitudinal and Hall resistances are quantized. We have shown that magnetic/non-magnetic modulated heterostructures are nice platforms to observe QAHE-related phenomena at relatively high temperature about 2 K [4]. In this talk, two schemes will be discussed for a control of edge current conduction; the one is in-plane magnetic domain control with magnetic force microscopy technique [5] and the other is out-of-plane antiparallel magnetization control in tricolor superlattice composed of Cr-doped and V-doped TI heterostructures [6]. In the former study, an edge current conduction was controlled by domain arrangement in Hall-bar structures. In the latter, antiparallel alignment of magnetization at top and bottom magnetic layers corresponds to axion insulator states, demonstrating colossal magnetoresistance. This talk will cover growth optimization of the heterostructures as well as device operations.
This work has been carried out in RIKEN CEMS under the collaboration with Prof. Tokura and Prof. M. Kawasaki group.

[1] C.-Z. Chang et al., Science 340, 167 (2013). [2] J. Checkelsky et al., Nature Phys. 10, 731 (2014). [3] C.-Z. Chang et al., Nature Mater. 14, 473 (2015). [4] M. Mogi et al., Appl. Phys. Lett. 107, 182401 (2015). [5] K. Yasuda et al., arXiv. 1707.09105v1 (2017). [6] M. Mogi et al., Sci. Adv. 3, eaa01669 (2017).