COUPLING BETWEEN SUPERCONDUCTIVITY AND STRUCTURAL DEFORMATION IN LA2-XSRXCUO4 (X-SIMILAR-TO-0.13)

Capacitance-dilatometer measurements of the anisotropic thermal expans ion on a superconducting single crystal of La2-xSrxCuO4 (x approximate ly 0.13) show large anomalies at the structural transition from the hi gh-temperature tetragonal to the low-temperature orthorhombic phase fo llowed by smaller anomalies of the opposite sign at the superconductin g phase transition. Neutron-diffraction experiments on the same crysta l indicate that at T(c) the tilt of the CuO6 octahedra related to the structural phase transition is frozen in.