Atsushi KAWAMOTO (Ochanomizu Univ.) Kazuya MIYAGAWA and Kazushi KANODA
[Phys. Rev. B 55, 14140 (1997)]
The electronic state of the deuterated salt of the organic system, (kappa)-(BEDT-TTF)2Cu[N(CN)2]Br, has been investigated by dc/ac susceptibility and 1H/13C NMR measurements. We found that the system is situated in the critical region of the transition between a superconducting phase with TC of ~ 11.5 K and an antiferromagnetic phase with TN of 14 ~ 15 K. It was also found that the rapid cooling through 80 K drives the superconducting phase into the magnetic phase, as is shown in Figure 1. That is considered to come from introduction of some lattice disorder to the system near the Mott transition.
Figure 1. ac susceptibility of deuterated (kappa)-(BEDT-TTF)2Cu[N(CN)2]Br crystal after slow or rapid cooling. The ac field is applied perpendicular to the layer. The results after rapid cooling are expanded in the inset.