Magnetic-field dependence of the phase-coherence length in the spin-density-wave state of tetramethyltetraselenafulvalinium nitrate, (TMTSF)2NO3

We have used electric-field-dependent measurements to probe the magnetic-field dependence of the phase-coherence length in the spin-density-wave (SDW) state of the organic conductor tetramethyltetraselenafulvalinium nitrate (TMTSF${)}_2$ ${\mathrm{NO}}_3$. The threshold electric field increases if a magnetic field is applied in the plane perpendicular to the highly conducting axis. The magnitude of the increase is angle-dependent and vanishes when the field is applied along the intermediate-conductivity axis. This behavior results from a reduction of the phase-coherence length of the SDW with strongly imperfect nesting in a magnetic field.