  We report angle-dependent magnetoresistance measurements on (TMTSF)2ClO4 that
provide strong support for a new macroscopic quantum phenomenon, the
interference commensurate (IC) effect, in quasi-one dimensional metals. In
addition to observing rich magnetoresistance oscillations, and fitting them
with one-electron calculations, we observe a clear demarcation of
field-dependent behavior at local resistance minima and maxima (versus field
angle). Anticipated by a theoretical treatment of the IC effect in terms of
Bragg reflections in the extended Brillouin zone, this behavior results from
1D-2D topological crossovers of electron wave functions as a function of field
orientation.
