Large anisotropic pressure effects in electron-doped Sm2-xCexCuO4-y

Measurements of the linear thermal expansion coefficients alpha(i) at the superconducting transition temperature T-c and measurements of the hydrostatic pressure dependence dT(c)/dP of high-quality single crystals of Sm2-xCexCuO4-y are presented. The uniaxial stress dependencies dT(c)/d sigma(i) are deduced thermodynamically from the observed discontinuous changes in alpha(i) at T-c. The uniaxial stress effects along the a and c crystallographic directions are dT(c)/d sigma(a) = -5.78 +/- 1.6 K/GPa and dT(c)/d sigma(c) = + 11.66 +/- 3.5 K/GPa, respectively. Their sum agrees well with the measured dT(c)/d P near zero. Thus, a decrease in the interlayer spacing is found to have a strong positive affect on T-c, and a decrease in the intralayer atomic spacing has a strong negative influence on T-c. (C) 1998 Elsevier Science B.V.