Hysteretic magnetic state in the organic tau-phase conductors

摘要

The tau-phase conductors are known to exhibit resistance upturn and negative magnetoresistance below T-min similar to 50 K. Well below T-min, at least in the range of about 1 to several K, a large hysteresis in the field sweep as well as angle sweep is observed in the configuration of current, I-parallel to or I-perpendicular to, and magnetic field, with B-parallel to or B-perpendicular to, where parallel to and perpendicular to refer to the two-dimensional a-b plane. Furthermore, with I-perpendicular to and B-parallel to, symmetry of the angular dependence of magnetoresistance varied between four-fold and two-fold depending on the region of T and B. Two-fold symmetry is hard to understand from the symmetry of the crystal and the relevant Fermi surface. Although many of the phenomena are unexplained, we believe that we have observed a new type of electronic property. (C) 1998 Elsevier Science S.A. All rights reserved. [References: 9]