A Comment on ``Superconducting-Normal Phase Transition in (Ba1-xKx)BiO3, x = 0.40, 0.47'' by B. F. Woodfield, D. A. Wright, R. A. Fisher, N. E. Phillips and H. Y. Tang, Phys. Rev. Lett. 83, 4622 (1999)

TL;DR

This paper comments on previous work, arguing that the superconducting phase transition in Ba1-xKxBiO3 is not of order II due to anomalous temperature dependence of critical fields, challenging earlier interpretations.

Contribution

It provides a critique of prior claims by analyzing critical field data, suggesting a different nature of the phase transition in Ba1-xKxBiO3.

Findings

Critical fields show anomalous temperature dependence.

Superconducting transition likely not of order II.

Challenges previous interpretations of the phase transition.

Abstract

This comment addresses criticisms of our PRL 82 (1999) p. 4532-4535 (cond-mat/9904288) raised by Woodfield et al. in their recent PRL. We find that the critical fields in single crystals of Ba1-xKxBiO3 (x = 0.4) have anomalous temperature dependecies which suggests that the superconducting phase transition in this material is not of order II.