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APS » Journals » Physical Review Letters » Superconductor-insulator phase separation induced by rapid cooling of $\kappa$-(BEDT-TTF)$_2$Cu[N(CN)$_2$]Br

January 2008, to be published in Physical Review B1

Superconductor-insulator phase separation induced by rapid cooling of $\kappa$-(BEDT-TTF)$_2$Cu[N(CN)$_2$]Br
O. J. Taylor, A. Carrington, and J. A. Schlueter

We present measurements of the low temperature specific heat of single crystals of $\kappa-$(ET)$_2$Cu[N(CN)$_2$]Br as a function of the cooling rate through the glasslike structure transition at $\sim$ 80K. We find that rapid cooling produces a small ($\lesssim 4$\%) decrease in the superconducting transition temperature accompanied by a substantial (up to 50\%) decrease in the normal-state electronic specific heat. A natural explanation of our data is that there is a macroscopic phase separation between superconducting and insulating regions in rapidly cooled samples.

© 2008 The American Physical Society.