J. Phys. IV France 114 (2004) 175
DOI: 10.1051/jp4:2004114041

Investigation of the field-induced phases in -(BETS) ₂Fe _xGa _1-xCl ₄

J.S. Brooks¹, S. Uji², E.S. Choi¹, H. Kobayashi^{3, 4}, A. Kobayashi⁵, H. Tanaka⁶ and M. Tokumoto<sup>6, 4

1</sup>  National High Magnetic Field Laboratory and Physics Department, Florida State University, Tallahassee, FL 32310, USA
²  National Institute for Materials Science, Tsukuba, Ibaraki 305-0003, Japan
³  Institute for Molecular Science, Okazaki, Aichi 444-8585, Japan
⁴  JST-CREST, Kawaguchi, Japan
⁵  Dept. of Chemistry, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan
⁶  Nanotechnology Research Institute, AIST, Tsukuba 305-8568, Japan

Abstract
We investigate the nature of the magnetoresistance in the antiferromagnetic, metallic, and field-induced superconducting ground states of the quasi-two dimensional organic-magnetic conductor -BETS ₂Fe _xGa _1-xCl ₄ for several alloy and experimental configurations. These include a consideration of scaling-type behaviour for x = 0.47 where the field is directed in plane along the c-axis. Here we find that both the antiferromagnetic and the superconducting states follow relatively simple scaling laws with magnetic field and temperature respectively over a considerable range of the phase diagram. An investigation of systematic rotation of the magnetic field with respect to both polar and azimuthal directions for x = 0.8 in high magnetic fields is also reported for both the metallic and antiferromagnetic phases. Key words. Organic conductors - field-induced superconductivity - antiferromagnetism.

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