MAGNETIZATION MEASUREMENTS IN THE 80 K TRANSFORMATION FOR DEUTERATED ORGANIC SUPERCONDUCTOR κ-(BEDT-TTF)2Cu[N(CN)2]Br

In this paper, we report systematic magnetic measurements on deuterated organic superconductor (κ-D8-Br)κ-(BEDT-TTF)2Cu[N(CN)2]Br. The irreversibility line Hirr(T) and the critical current density Jc were studied. Our results show the strong dependence of Hirr(T) and Jc on the cooling rate. The structural transformation which occurs at the vicinity of 80 K very strongly influences the physics of vortex lattice and the associated magnetic behavior. The irreversible magnetization becomes null at Hirr and vortices are not pinned; therefore they can displace more freely for an increase of the field or the temperature.

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