Commensurate fine structure in angular-dependent studies of (TMTSF)₂ClO₄

Clear fine-structure oscillations in magnetoresistance and torque magnetization are observed at low temperatures in the anisotropic organic superconductor (TMTSF)₂ClO₄ as a function of sample orientation in a fixed magnetic field. At 0.1 K, these fine structures appear as resistance minima and torque maxima at specific orientations of the field in the b^*-c^* sample plane, with one-to-one correspondence. The angular positions of the feature are independent of magnetic field, temperature, and cooling rate (disorder), while their magnitudes depend strongly on all three. We compare these observations with a recent prediction by Lebed’ and Bak of resistance, but not magnetization, anomalies expected to arise at special ‘‘magic’’ orientations in field.