Topological superconductivity in Sr0.1Bi2Se3 | Argonne National Laboratory

June 1, 2018

In a study published in Scientific Reports, researchers reported results support the recently proposed odd-parity nematic state characterized by a nodal gap of Eu symmetry in SrxBi2Se3.

(left) The threefold symmetric basal plane. (right) Schematic presentation of the two-dimensional Δ4 superconducting gap with respect to a spherical Fermi surface. The Δ4 gap has basis functions (Δ4x) with nodes on the mirror plane [depicted in (c)] and (Δ4y) with deep minima in the perpendicular direction. This gap breaks the threefold crystal symmetry and gives rise to the nematic state with twofold symmetry.

Scientific Achievement

We revealed a pronounced two-fold, in-plane superconducting anisotropy in trigonal Sr_0.1Bi₂Se₃ in the absence of any discernable normal-state anisotropy or crystal lattice distortions.

Significance and Impact

Our results support the conclusion that the two-fold anisotropy is caused by the nematic nodal D4x gap and identify Sr_0.1Bi₂Se₃ as a bulk topological superconductor.

Research Details

Angular dependent magneto-transport and magnetization measurements reveal a robust two-fold symmetric superconducting and isotropic normal state.
High-resolution synchrotron X-ray diffraction confirms an essentially ideal trigonal crystal structure.

DOI: 10.1038/s41598-018-26032-0

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