Control of the nematic superconductivity of Sr<i>_x</i>Bi₂Se₃ and its domains by uniaxial strain

Recently, nematic superconductivity, exhibiting spontaneous rotational symmetry breaking in bulk superconducting quantities, has been discovered in A_xBi₂Se₃ (A = Cu, Sr, Nb) [1]. In an analogy to the nematic liquid crystals accompanying high controllability of the order-parameter directions, similar controllability can be expected for nematic superconductivity. Indeed, we succeeded in controlling nematic superconductivity in Sr_xBi₂Se₃ via external uniaxial strain [2]. By applying uniaxial strain in situ along the a axis, we reversibly controlled the superconducting nematic domain structure, from the multi-domain state under zero strain into a nearly single-domain state under 1% uniaxial compression. This is the first achievement of domain engineering using nematic superconductors.
[1] For a recent review, see S. Yonezawa, Condens. Matter 4, 2 (2019).
[2] I. Kostylev, S. Yonezawa et al., Nature Commun. 11, 4152 (2020).