J. Phys. IV France 114 (2004) 297
DOI: 10.1051/jp4:2004114064

The pressure-temperature phase diagram of pressure induced organic superconductors -(BDA-TTP) ₂MCl ₄ (M = Ga, Fe)

E.S. Choi^{1, 1}, D. Graf¹, J.S. Brooks¹, J. Yamada² and M. Tokumoto<sup>3

1</sup>  National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA
²  Dept. of Material Science, Graduate School of Science, Himeji Institute, Hyogo 678-1297, Japan
³  Natotechnology Institute, AIST, Tsukuba 305-8568 and JST-CREST, Kawaguchi 332-0012, Japan

Abstract
We investigate the pressure-temperature phase diagram of -(BDA-TTP) ₂MCl ₄ ( M=Ga, Fe), which shows a metal-insulator (MI) transition around 120 K at ambient pressure. By applying pressure, the insulating phase is suppressed. When the pressure is higher than 5.5 kbar, the superconducting phase appears in both salts with Tc 3 K for M=Ga and 2.2 K for M=Fe. We also observed Shubnikov-de Haas (SdH) oscillations at high magnetic field in both salts, where the SdH frequencies are found to be very similar each other. Key words. organic superconductor, pressure, phase diagram.

© EDP Sciences 2004