Rise of topology in condensed matter: balancing robustness against disorder with control of electronic properties

Eklavya Thareja

University of South Florida

Recently, the field of condensed matter has gone through a revolution determined by novel insights into the topological aspects of many-body systems. While these aspects are of fundamental interest, growing interest in topological systems is due to their promise of broad applications, from spintronics to quantum computing. The applications rely on the robustness of topologically protected electronic states against various forms of disorder. However, control of the macroscopic properties of these electronic states is just as important. We focus on already physically realized topological phases such as topological insulators and Weyl semimetals. Our work shows that universally present crystal defects, such as surface steps and planar defects, host spin-textured localized states in these systems. These states give rise to spin accumulation and non-dissipative charge currents in the system due to a unique property, spin-momentum locking, present in these topological systems. This property enables considerable control of the spin accumulation and currents by simply using an externally applied magnetic field, which brings us closer to building valuable functionalities.