Seminars & Lectures
* TITLE | Specific heat of NaxCoO2yH2O: implications for unconventional superconductivity | ||||||
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* DATE / TIME | 2004-05-11, 10:30 am | ||||||
* PLACE | Bldg 3, Room#201, POSTECH | ||||||
* ABSTRACT | |||||||
Comprehensive magnetic field (H) dependence of the low-temperature specific heat C(T,H) in NaxCoO2•yH2O is presented. At H=0, a very sharp anomaly was observed at T=4.7 K indicating the existence of bulk superconductivity. There exists the T2 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 % to 50% based on the consideration of entropy balance at Tc for the second-order superconducting phase transition. The Hc2(T) Shows an abrupt change of slope, which could be due to either anisotropy of Hc2 or the transition to a second superconducting phase. |