We have measured the specific heat of a single crystal of YBa2Cu3O7−δ. Thermodynamic fluctuations, evident in deviations of the data from a BCS-like step, are well described by 3-dimensional (3D) Gaussian fluctuations. The results imply that the number of components of the order parameter is 7±2. When a magnetic field is applied parallel to the c axis, the specific heat peak broadens and decreases in amplitude, with little shift in position. The difference between the zero field specific heat and that measured in a field is found, however, to satisfy a scaling relation suggesting critical, rather than Gaussian, fluctuations.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering