J. Phys. IV France
Volume 114, April 2004
Page(s) 357 - 359

J. Phys. IV France
114 (2004) 357
DOI: 10.1051/jp4:2004114082

Phase separation behaviour on $\kappa $-(BEDT-TTF) 2 Cu [N(CN) 2]Br

S. Okitsu, A. Kawamoto and K. Kumagai

Division of Physics, Graduate School of Science, Hokkaido University; Kita 10 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan

The system of the deuterated $\kappa $ -(BEDT-TTF- d[n,n])2Cu[ N(CN) 2] Br is situated in the critical region between the superconducting(SC) phase and the antiferromagnetic insulator (AFI) phase, and is just on the Mott type critical boundary of paramagnetic metal (PM) phase and paramagnetic insulator (PI) phase . We perform two single-crystal 13C-NMR studies on the non and the fully deuterated $\kappa $- (BEDT-TTF) 2Cu[ N(CN) 2] Br at low temperature with the applied field 9.4T. We found two new experimental results. One is that the phase separation is found in $\kappa $ -(BEDT-TTF- d[0,0])2Cu[ N(CN) 2] Br salt, like partially deuterated $\kappa $ -(BEDT-TTF) 2 Cu[ N(CN) 2] Br salt. The other is that the phase separation is observed at around T* with the applied field parallel to the conducting layer, unlike partially deuterated $\kappa $ -(BEDT-TTF- d[n,n])2 Cu[ N(CN) 2] Br. The former result suggests the field induces AF transition. the latter result suggests there is the field direction dependence of the M-I phase separation behavior in $\kappa $- (BEDT-TTF- d[4,4])2 Cu[ N(CN) 2] Br. Key words. $\kappa $-(BEDT-TTF) 2X, field-dependence, superconductivity, anti-ferromagnetism, phase separation.

© EDP Sciences 2004