There are spectacular resistance anomalies when a magnetic field coincides with crystal directions between one dimensional chains! Here is the resistance data and a fit to a simple model explained below.

At these magic angles the temperature dependence is metallic (resistance decreases as temperature decreases. At other angles the resistnce increases with decreasing temperature.

The model is best illustrated by plotting the z axis conductivity instead of resistance. We see that in high field there are contributions which come from tunneling along the field lines in the directions between chains. The truly unusual part of this is that there is a sizable contribution from tunneling between chains which are not along the conductivity (z) direction. We suggest that when chains are decoupled we have an insulator in all directions with a gap at the Fermi Energy. When the chains are coupled we have a metal in all directions.

The temeprature dependence is fit with the same parameters as the first figure above and using R(T,H=0).