Electronic properties of La2-xSrxCuO4 high-Tc superconductors

The basic macroscopic properties of the high-Tc superconductors La2-xSrxCuO4 (x=0.0750.20) with bulk transition temperatures up to 37.5 K were studied. The upper and lower critical fields, specific heat, Meissner effect, and electric resistivity were measured and extreme type-II behavior with large upper-critical-field slopes is observed. The density of states at EF is caLculated from three different sets of experimental quantities (BCS=61.5 mJ/mole? sup 2). The critical temperatures of (La, Sr)2CuO4 and Ba(Pb,Bi)O3 are 3 times higher than those of other superconductors with comparable values of, which empirically distinguishes them as a separate class of superconductors.