Lack of coupling between superconductivity and orthorhombic distortion in stoichiometric single-crystalline FeSe
Lack of coupling between superconductivity and orthorhombic distortion in stoichiometric single-crystalline FeSe
The coupling between superconductivity and othorhombic distortion is studied in vapor-grown FeSe single crystals using high-resolution thermal-expansion measurements. In contrast to the Ba122-based (Ba122) superconductors, we find that superconductivity does not reduce the orthorhombicity below Tc. Instead we find that superconductivity couples strongly to the in-plane area, which explains the …