Simple fit for magic-angle magnetoresistance in (TMTSF)₂PF₆

The angular-dependent magnetoresistance in the Bechgaard salts (TMTSF)₂X (X=PF₆,ClO₄, etc.) is characterized by sharp dips when the field is aligned along lattice vectors. Although magic-angle effects were originally predicted by Lebed, they remain largely unexplained. Here we present detailed interplane transport data and show that a simple model involving conductivity contributions from transfers between neighboring chains, which are individually destroyed by a perpendicular field, fits most c-axis data remarkably well. The fitting illustrates what can be explained by classical transport and what cannot—a dominant term from hopping perpendicular to the current direction. Combined with the observation that the fitting also “works” for a-axis data, this suggests a different interpretation: The quasi-one-dimensional system is insulating and any unnesting transfer makes it metallic.