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Specific heat of unconventional superconductivity in NaxCoO2-yH2O

H. D. Yang·J. -Y. Lin·C. P. Sun·Y. C. Kang·K. Takada·T. Sasaki·H. Sakurai·E. Takayama-Muromachi
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Abstract

Comprehensive studies of the low-temperature specific heat C(T,H) in NaxCoO2-yH2O are presented. At H=0, a very sharp anomaly was observed at T=4.7 K indicating the existence of bulk superconductivity. There exists the T^2 term in C(T,H=0) in the superconducting state manifesting the line nodal superconducting order parameter. The superconducting volume fraction is estimated to be 26.6 % based on the consideration of entropy conservation at Tc for the second-order superconducting phase transition. An abrupt change of the slope in Tc(H) was observed. Possible scenarios such as the multiple phase transitions in the mixed state are discussed.

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H. D. Yang, J. -Y. Lin, C. P. Sun, Y. C. Kang, K. Takada, T. Sasaki, H. Sakurai, E. Takayama-Muromachi. 2004-05-05. Specific heat of unconventional superconductivity in NaxCoO2-yH2O. https://arxiv.org/abs/cond-mat/0308031

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