Oral: Atomic scale insights into magnetic topological materials.

Incorporating magnetic order in a topological insulator material offers a direct route in observing quantum anomalous hall effect phenomena. Family of compounds based on doping of bismuth antimony telluride (Bi_xSb_2-xTe₃) with magnetic transition metal atoms (such as manganese, chromium, vanadium, etc.) constitute model systems for studying such topologically protected edge states. The unit cell of bismuth telluride comprises of five atomic layers of chemically bonded Bi and Te, stacked in the c-direction interacting through van der Waals forces. We use molecular beam epitaxy for layer-by-layer growth of doped Bi_xSb_2-xTe₃ that enables us to control the magnetic ordering depending on the odd or even number of substitutionally doped layers. Here, we present a systematic study on these quantum hall materials investigated by means of ultra-low temperature (10 mK) scanning tunneling microscopy and in-plane transport measurements in presence of external magnetic field.

*Supported in part by the Office of Naval Research Grant Number N00014-23-1-2477