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계산과학부

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세미나

Seminar
FIELD Computational Sciences
DATE November 22 (Fri), 2019
TIME 14:00-17:00
PLACE 1423
SPEAKER Gil-Ho Lee
HOST Son, Young-Woo
INSTITUTE POSTECH
TITLE Evidence of Higher Order Topology in Multilayer WTe2 from Josephson Coupling through Anisotropic Hinge States
ABSTRACT The noncentrosymmetric Td-WTe2, previously known as a type-II Weyl semimetal, is expected to have higher order topological phases with topologically protected, helical one-dimensional (1D) hinge states when their scarcely separated Weyl points get annihilated. However, the detection of these hinge states is difficult in the presence of the semimetallic behaviour of the bulk. Here, we spatially resolved the hinge states by analysing the magnetic field interference of supercurrent in Nb-WTe2-Nb proximity Josephson junctions. The Josephson current along the a-axis of the WTe2 crystal, but not along the b-axis, showed sharp enhancements at the edges of the junction; the amount of enhanced Josephson current was comparable to the upper limits of a single 1D conduction channel. Our experimental observations provide evidence of the higher order topological phase in WTe2 and its corresponding anisotropic topological hinge states, in good agreement with theoretical calculations. Our work paves the way for hinge transport studies on topological semimetals in superconducting heterostructures, including their topological superconductivity.
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