Dresden 2020 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 38: Topological Superconductors

TT 38.2: Vortrag

Mittwoch, 18. März 2020, 11:30–11:45, HSZ 103

Structurally-driven nematicity of odd-parity superconductivity in SrxBi2Se3 — •Aleksandr Kuntsevich, Yuri Selivanov, Victor Martovitskii, and Aleksandr Rakhmanov — P.N. Lebedev Physical Institute, 119991, Moscow, Russia

Superconductivity(SC) in doped (by Cu, Sr or Nb) topological insulator Bi2Se3 attracts a great deal of attention as odd-parity topological one, with an exotic nematic vector order parameter.On a structural level it is unknown where exactly the dopant atoms are located in the lattice and how this placement controls SC properties.

SrxBi2Se3 is the most structurally perfect member of this family, it demonstrates stability of SC, and ∼100% SC fraction. We improved the crystalline quality, showed that that SC in SrxBi2Se3 is induced by very low doping level, and strongly depends on the specific arrangement of Sr atoms in the host matrix [1].

We also managed to obtain purely single-block crystals. The x-ray diffraction shows that these single crystals are either weakly stretched or compressed uniaxially in the basal plane. In the SC state, the upper critical field Hc2 has a twofold rotational symmetry and depends on the sign of the strain: in the stretched samples the maximum of Hc2 is achieved when H is transverse to the strain axis, while in the compressed samples this maximum is observed when the field is along the strain direction. This result is naturally explained within the nematic SC coupled to the strain. This observation is a novel experimental evidence for the odd-parity SC in SrxBi2Se3[2].

[1] AYK et al Materials12, 3899,2019

[2] AYK  et al PRB100, in press,2019

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