Mechanisms of nonthermal destruction of the superconducting state and melting of the charge-density-wave state by femtosecond laser pulses

摘要

The processes leading to nonthermal condensate vaporization and charge-density-wave (CDW) melting with femtosecond laserpulses is systematically investigated in different materials. We find that vaporization is relatively slow (τ_v ～ 1 ps) and inefficient in superconductors, exhibiting a strong systematic dependence of the vaporization energy U_v on T_c. In contrast, melting of CDW order proceeds rapidly (τ_m = 50-200 fs) and more efficiently. A quantitative model describing the observed systematic behavior in superconductors is proposed based on a phonon-mediated quasiparticle (QP) bottleneck mechanism. In contrast, Fermi-surface disruption by hot QPs is proposed to be responsible for CDW state melting.