University of Connecticut

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Condensed Matter Physics Seminar

Tuesday, November 13, 2018
2:00pm – 3:00pm

Storrs Campus
Gant West (Physics Building), P121

Dr. Turgut Yilmaz, Department of Physics, University of Connecticut

Topological insulators and their interaction with magnetic impurities and superconductors

Topological properties of materials have recently attracted much attention in the condensed matter physics community due, in part to their possible applications in quantum electronic devices. In particular, topological insulators (TIs) that possess gapless surface states that are topologically protected and can lead to dissipationless quantum electronics. TI’s surface state exhibit relativistic momentum dispersion with the Dirac point (DP) located at the time reversal invariant momenta point while the bulk bands are inverted and gapped [1]. Currently, two majority experimental efforts have concentrated on inducing the magnetic and superconducting properties in TI, which would lead to the experimental realizations of quantum anomalous Hall effect (QAHE) and Majorana fermions, respectively [2-3].

Magnetism can be induced in TIs by incorporating impurities into the bulk or on the surface of TIs. If there is a net out-of-plane magnetic moment, an energy gap opens at the DP due to broken time reversal symmetry, which would give rise to QAHE. On the other hand, the superconductivity in can be induced in TI through the proximity effect by growing TIs on the surface of a superconductor. Both, the gapped DP and the superconductivity can be probed by angle-resolve photoemission spectroscopy (ARPES). In this talk, I will present our photoemission studies on the search of broken time reversal symmetry in magnetic TIs and proximity induced superconductivity in TI/superconductor heterostructures. Also, the experimental setup to grow and study TIs at the Physics Department of the University of Connecticut will be presented.

[1] L. Fu, C. L. Kane, and E. J. Mele, Phys. Rev. Lett. 98, 106803 (2007).

[2] X.-L. Qi and S.-C. Zhang, Rev. Mod. Phys. 83, 1057 (2011).

[3] T. Yilmaz, et al., Appl. Surf. Sci. 407, 371 (2017).


Prof. B. Sinkovic

Physics Department (primary)

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