Magnetic-Field Variations of the Pair-Breaking Effects of Superconductivity in (TMTSF)2ClO4
We have studied the onset temperature of the superconductivity T c onset of the organic superconductor (TMTSF) 2 ClO 4 , by precisely controlling the direction of the magnetic field H . We compare the results of two samples with nearly the same onset temperature but with different scattering relaxation time τ. We revealed a complicated interplay of a variety of pair-breaking effects and mechanisms that overcome these pair-breaking effects. In low fields, the linear temperature dependences of the onset curves in the H – T phase diagrams are governed by the orbital pair-breaking effect. The dips in the in-plane field-angle φ dependence of T c onset , which were only observed in the long-τ sample, provides definitive evidence that the field-induced dimensional crossover enhances the superconductivity if the field direction is more than about 19° away from the a axis. In the high-field regime for H ∥ a , the upturn of the onset curve for the long-τ sample indicates a new superconducting state that overcomes t...