Nonequilibrium superconductivity based on quasithermal phonon and quasiparticle distributions

A new phenomenological model describing nonequilibrium superconductivity is proposed which is characterized by the introduction of a quasithermal distribution of phonons with energies of 0--{∞}. The model exhibits μ*-model-like and T*-model-like {Δ} vs n and μ* vs n characteristics when the excess quasiparticle density n is low and high, respectively. The estimated critical density nc for the onset of instability is much lower than that of the μ* model. These results are in fairly good agreement with the experimental results reported by Willemsen and Gray, and Akoh and Kajimura.