Symmetry change in the angular dependence of magnetoresistance of the two-dimensional organic conductor, tau-(EDO-S, S-DMEDT-TTF)(2)(AuBr2)(AuBr2)(y), (y similar to 0.75)

Angular dependence of magnetoresistivity, rho(c)(phi), of a quasi-two-dimen sional organic conductor, tau-(EDO-S, S-DMEDT-TTF)(2)(AuBr2)(AuBr2)(y), (y similar to 0.75), where EDO-S, S-DMEDT-TTF is ethylenedioxy-S, S-dimethylet hylenedithio-tetrathiafulvalene was measured for the magnetic field and the electrical current parallel and perpendicular to the most conducting ab pl ane. The magnetoresistance is negative in the semiconducting range below ab out 50 K. It was found that the period of rho(c)(phi) changes from 90 degre es at 5.0 T to 180 degrees at 0.5 T and the principal axis of rho(c)(Q) at 0.5 T depends on the field-orientation at 5.0 T. The change in the period a nd the principal axis of rho(c)(phi) is discussed in terms of formation and reorientation of magnetic domains.