Abstract
We suggest that the transition to superconductivity in a single crystal of with , and having critical fields with anomalous temperature dependencies and vanishing discontinuities in specific heat and magnetic susceptibility, may well be an example of a fourth order (in Ehrenfest's sense) phase transition. We have derived a free energy functional for a fourth order transition and calculated (for the temperature range ) the temperature dependence of the critical fields. We find , , and in general agreement with experiments.
- Received 12 October 1998
DOI:https://doi.org/10.1103/PhysRevLett.82.4532
©1999 American Physical Society