We investigate the specific heat of ultra-pure single crystals of Sr2RuO4, a leading candidate of a spin-triplet superconductor. We for the first time obtained specific-heat evidence of the first-order superconducting transition below 0.8 K, namely divergent-like peaks and clear hysteresis in the specific heat at the upper critical field. The first-order transition occurs for all in-plane field directions. The specific-heat features for the first-order transition are found to be highly sensitive to sample quality; in particular, the hysteresis becomes totally absent in a sample with slightly lower quality. These thermodynamic observations provide crucial bases to understand the unconventional pair-breaking effect responsible for the first-order transition.
@article{arxiv.1406.4640,
title = {Specific-heat evidence of the first-order superconducting transition in Sr2RuO4},
author = {Shingo Yonezawa and Tomohiro Kajikawa and Yoshiteru Maeno},
journal= {arXiv preprint arXiv:1406.4640},
year = {2014}
}
Comments
5 pages, 4 figures; to appear in the Letter Section of J. Phys. Soc. Jpn