The specific heat C of YBa2Cu3O7-δ (δ=0, 0.69, 0.91), Y1.1Ba1.9Cu3O7-δ and BaCuO2+x has been investigated in magnetic fields up to 6 T. In addition to the γ*T term and the upturn, characteristic behaviors of C/T consisting of the increase of γ* with magnetic fields, an appearance of a broad hump and a rapid decrease of C/T toward zero at the lowest temperatures are observed in all the YBa2Cu3O7-δ samples investigated. BaCuO2+x, one of the possible impurity phases included in the Y-Ba-Cu-O system, also shows a similar behavior of C/T as YBa2Cu3O7-δ. Particularly, BaCuO2+x explains the anomalous phenomenon observed in YBa2Cu3O6.31 at 6 T that the C/T at 1.5 K attains to the γ* value at 0 T. The γ* value is attributed to the BaCuO2+x included in the matrix.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering