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Controlling a quantum point junction on the surface of an antiferromagnetic topological insulator

Date and Time: Tuesday, September 15, 2020, 01:30pm -
Location: Zoom

Speaker: Nicodemos Varnava (Department of Physics & Astronomy, Rutgers University)

The abstract notion of topology has led to profound insights into real materials. Notably, the surface and edges of topological materials can host physics, such as unidirectional charge or spin transport, that is unavailable in isolated one- and two-dimensional systems. However, to fully control the mixing and interference of edge-state wave functions, one needs robust and tunable junctions. In this talk, I will present a way to achieve this control using an antiferromagnetic topological insulator that supports two distinct types of gapless unidirectional channels on its surface, one from antiferromagnetic domain walls and the other from single-height steps. The distinct geometric nature of these edge modes allows them to intersect robustly to form quantum point junctions[1], and their presence at the surface makes them subject to control by magnetic and electrostatic tips like those used in scanning probe microscopes. Prospects for realizing such robust and tunable quantum point junctions are encouraged by recent experimental developments in the field of magnetic topological insulators[2,3,4,5] and could potentially lead to exciting applications in quantum computing and sensing.

[1] arXiv:2008.03316
[2] Nature 576, 416–422 (2019)
[3] Science 367, 895– 900 (2020)
[4] Nature Physics (2020), 10.1038/s41567-020-0998-2.
[5] Phys. Rev. Lett. 125, 037201 (2020)

Host: David Vanderbilt

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