A DIMENSIONAL CHARACTERISTIC IN THE SPECIFIC-HEAT OF HIGH-TEMPERATURESUPERCONDUCTORS

The specific heat C of superconductors is strongly depressed just belo w the transition temperature by an increase of the magnetic field Delt a B. A measurement of the function \partial derivative(C/T)/partial de rivative B\ for different magnetic fields at T approximate to T-c, whi ch can be approximated by a Lorentzian of half-height width Delta T(B) proportional to B-n, is found to be a direct way of determining the d imensionality of a superconducting system in the LLL (lowest Landau le vel) approximation, with n = 1/2 for 2D and n = 2/3 for 3D. No baselin e subtraction is required. Examples are given using high resolution sp ecific heat measurements between 0 and 16 tesla on YBa2Cu3O7-delta (YB CO) and Bi2Sr2CaCu2O8 (BSCCO) single crystals. The temperature T-cB(B) of the minimum of \partial derivative(C/T)/partial derivative B\ can be related to the mean-held critical temperature T-c(B) in the framewo rk of the theory of Tesanovic at high fields.