Amorphous Topological States in Shiba Glasses

LTL Quantum Physics Seminar (Nanotalo). Speaker: Mr. Alex Westström (Aalto University, Finland).

Topological states of matter support quantized nondissipative responses and exotic quantum particles that cannot be accessed in mundane materials. Their exceptional properties and application potential has triggered a large-scale search for new topological states and material realizations. In this work, we identify a Shiba glass as a qualitatively new type of topological state which is amorphous. This system consists of an ensemble of randomly distributed magnetic atoms on a superconducting surface with a Rashba spin-orbit coupling. The collection of magnetic moments give rise to subgap Yu-Shiba-Rusinov states that form a topologically nontrivial phase at a critical density despite a complete absence of any spatial symmetry. The studied system demonstrates the physical feasibility of amorphous topological systems, and that the typically stringent quality requirements imposed by crystalline order can be circumvented when fabricating topological systems.