Evidence for coherent interchain electron transport in quasi-one-dimensional molecular conductors

The angular magnetoresistance of the organic superconductor (TMTSF)₂ReO₄ was measured up to 13.5 T. Exceptionally well-resolved angular magnetoresistance oscillations were observed, and analysis of these oscillations revealed several important features concerning interlayer transport. Lebed resonance dips up to the twenty-first order and subresonance dips corresponding to p/q=nonintegers were observed. The key finding of this work was that, unlike other organic conductors of the form (TMTSF)₂X, (TMTSF)₂ReO₄ exhibits the Lebed resonance effect only when both p and q are odd integers. A simple explanation for this phenomenon, based on the unique anion ordering with wave vector (0, 1/2, 1/2), is presented. This simple model can be applied to all Bechgaard salts. The analysis shows that interchain electron transport is coherent even though chains are as far apart as 200 Å or more.