Discontinuity of the isothermal elastic compliance across the superconducting transition in Y₁Ba₂Cu₃O_7-δ

The discontinuity of the isothermal elastic compliances across the superconducting transition are calculated for a single crystal. The discontinuity is based on measurements of jumps in the thermal expansion coefficient matrix, the adiabatic elastic compliances and the specific heat for the second order superconducting phase transformation. It is shown that the jump in the adiabatic compliance is significantly smaller than the jump in the isothermal compliance. Wide differences exist between the reported values of the thermal expansion coefficients and the measured jumps in the leastic compliances. These physical differences might result from the spinoidal decomposition of Y₁Ba₂Cu₃O_7-δ into a series of homologous ordered phases at low temperatures, with each phase having significantly different physical properties with relatively no change in the microscopic transition temperature.