Magnetic field orientation dependent ground states in (TMTSF)2PF6

We report anisotropic and angular dependent magneto-resistance measurements in the “normal” state of TMTSF2PF6 under pressure at low temperature. The most striking feature of this study occurs below 5K where we observe metallic behavior (dR/dT>0) when the field is aligned along intermolecular tunneling directions (Lebed magic angles) and non-metallic behavior (dR/dT>0) for other orientations. Previous results showed this behavior along the most conducting a direction, but here we show that the b and c (interplane) directions also exhibit this metallic to non-metallic transition with angle. At higher temperatures (~15–20K) there is a resistance minimum in the conducting (a-b) plane which is absent in the interplane (c) direction. Since we expect phase transitions, or other changes in the electronic state, to be observable in all directions, this observation implies that the nature of the ground state is reflected in the 5K magic angle effects and is determined by interplane decoupling rather than in-plane dimensionality crossovers.