[Seminar] "Uniaxial-strain Control of Nematic Superconductivity in SrxBi2Se3" by Dr. Ivan Kostylev
Dr. Ivan Kostylev, Kyoto University
Title: Uniaxial-strain Control of Nematic Superconductivity in SrxBi2Se3
I. Kostylev1, S. Yonezawa1, Z. Wang2,3, Y. Ando2, Y. Maeno1
1 Department of Physics, Kyoto University, Kyoto 606-8502, Japan
2Institute of Physics II, University of Cologne, Köln 50937, Germany
3Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement, Ministry of Education (MOE), School of Physics, Beijing Institute of Technology, Beijing 100081, P. R. China
Nematic states are characterized by rotational symmetry breaking without translational ordering. Recently, nematic superconductivity, in which the superconducting gap spontaneously lifts the rotational symmetry of the lattice, has been discovered [1-3]. In nematic superconductivity, multiple superconducting domains with different nematic orientations can exist, and these domains can be controlled by a conjugate external stimulus. Domain engineering are quite common in magnets but has not been achieved in superconductors. However, the pairing mechanism and the mechanism determining the nematic orientation remain unresolved.
A first step is to demonstrate control of the nematicity, through application of an external symmetry-breaking field, to determine the sign and strength of coupling to the lattice. Here, we report control of the nematic superconductivity and their domains of SrxBi2Se3, through in situ externally-applied uniaxial stress using a novel uniaxial strain cell (Fig. 1) [4, 5]. The suppression of subdomains indicates that it is the ∆4y state that is most favored under compression along the basal Bi-Bi bonds. This fact allows us to determine the coupling parameter between the nematicity and lattice distortion.
These results provide an inevitable step towards microscopic understanding and future utilization of the unique topological nematic superconductivity .
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