Resonant angular magnetoresistance in the ac-plane of the Bechgaard salts: Comparative studies

Lebed resonance phenomenon which manifests sharp resistance minima at angles where the magnetic field imposes electrons a periodic motion on the Fermi surface, is readily observed in most of Bechgaard salts such as (TMTSF) ₂ClO₄, (TMTSF)₂PF₆, (TMTSF) ₂ReO₄. On the other hand, another type of oscillatory behavior, observed when the magnetic field rotates from the most conducting direction towards the least conducting direction, in the acplane, is found to vary much from one compound to another, having been clearly observed only in (TMTSF)₂ClO₄. We have performed a systematic study of both the bc- and ac-rotation measurements and report that the ac-plane resonances are also omnipresent and universal in all the three compounds. Difference among compounds, notably the strength of the coherence peak may be used to account for the evolution of coherence from one compound to another.