Specific heat of La_2−xSr_xCuO₄: Volume fraction of superconductivity; Possible structural transition at 45K

Specific heat measurements on La1.85Sr0.15CuO4 show a linear correlation of the zero-field low-temperature linear term with the discontinuity at Tc, each of which provides a measure of the superconducting volume fraction. The correlation leads to an estimate of the normal-state density of electronic states which, together with the band structure calculated value, gives an electron-phonon interaction parameter that is too small to account for the superconductivity. For a sample with x=0.30 a magnetic field insensitive anomaly in specific heat near 45K was observed which may be related to a structural phase transition. © 1990, Elsevier Science Publishers B.V. (North-Holland). All rights reserved.