Transient cooling of quasiparticles in K3C60 by mid-infrared laser pulses
Prof. Dr. Michele Fabrizio, International School for Advanced Studies SISSA, Trieste, Italy
We propose an explanation of the transient superconducting-like optical behavior observed at temperatures as high as ten times Tc in K3C60 irradiated by mid-infrared laser pulses. In our theory the phenomenon is due to the laser pulse effectively cooling down low energy quasiparticles much below the external temperature. The mechanism is quite general and relies on the existence of localised excitations, in K3C60 these are spin-triplet excitons, that act as entropy sink when the laser is on, while, when the laser is off, they release back the stolen entropy very gradually.