Van der Waals Topological Magnets and Superconductors

Dmitry Ovchinnikov
Dr. Andrew Meng

Abstract: The breaking of time-reversal symmetry in topological insulators leads to novel quantum states of matter. One prominent example at the two-dimensional limit is the Chern insulator, which hosts dissipationless chiral edge states at sample boundaries. These chiral edge modes are perfect one-dimensional conductors whose chirality is defined by the material magnetization and in which backscattering is topologically forbidden. Recently, van der Waals topological magnet MnBi2Te4 emerged as a new solid-state platform for studies of the interplay between magnetism and topology. In this talk, I will present an overview of our progress toward controlling topological phase transitions and chiral edge modes in MnBi2Te4 as well as discovering new quantum states in this material family. First, I will establish how topological properties are intimately intertwined with magnetic states. I will then demonstrate electrical control of the number of chiral edge states and the discovery of chiral edge modes along crystalline steps between regions of different thicknesses and how these modes can be harnessed for the engineering of simple topological circuits. Finally, I will discuss the engineering of the superconducting state in topological insulators and demonstrate Pauli paramagnetic limit violation in atomically thin flakes of a topological superconductor candidate.

Bio: Dmitry Ovchinnikov earned his Ph.D. from the Institute of Electrical and Micro Engineering at École Polytechnique Fédérale de Lausanne (EPFL), Switzerland in 2017. During his Ph.D., he conducted experiments on two-dimensional semiconductors and developed techniques to modulate disorder in low-dimensional systems. His thesis earned him the EPFL EDMI PhD thesis distinction award and the Gilbert Hausmann PhD thesis award. He received an early postdoc Swiss National Science Foundation (SNSF) mobility fellowship to research nanoscale van der Waals magnetic devices at the University of Washington with Prof. Xiaodong Xu. Currently, Dmitry is an Assistant Professor at the Department of Physics and Astronomy at the University of Kansas. His work involves exploring the fundamental physics and applications of topological magnets, superconductors, and correlated states in low-dimensional quantum materials.