In order to investigate the possible inhomogeneity of superconductivity from measurements reflecting bulk properties of a sample, we have measured the magnetic susceptibility, χ, and specific heat of slightly overdoped and underdoped Y0.8Ca0.2Ba2Cu3O 7-δ polycrystals. The absolute value of χ at 2 K, |χ2κ|, on field cooling reflecting the superconducting (SC) volume fraction has been found to decrease monotonically with decreasing hole-concentration. From the specific heat measurements, on the other hand, it has been found that the so-called Sommerfeld constant is not zero but has a finite value even in the SC state. These results are quite similar to those observed in La2-xCuC4 and suggest that a phase separation into SC and normal-state regions takes place in Y0.8Ca 0.2Ba2Cu3O7-δ as well. It appears that the phase separation is a generic feature in high-Tc cuprates.
ASJC Scopus subject areas
- Physics and Astronomy(all)