Time-resolved photoexcitation of the superconducting two-gap state in MgB2 thin films.
Femtosecond pump-probe studies show that carrier dynamics in MgB2 films is governed by the sub-ps electron-phonon (e-ph) relaxation present at all temperatures, the few-ps e-ph process well pronounced below 70 K, and the sub-ns superconducting relaxation below T(c). The amplitude of the superconducting component versus temperature follows the superposition of the isotropic dirty gap and the three-dimensional pi gap dependences, closing at two different T(c) values. The time constant of the few-ps relaxation exhibits a double divergence at temperatures corresponding to the T(c)'s of the two gaps.
Xu
Y
Y
Department of Electrical and Computer Engineering and Laboratory for Laser Energetics, University of Rochester, Rochester, NY 14627-0231, USA.
Khafizov
M
M
Satrapinsky
L
L
Kús
P
P
Plecenik
A
A
Sobolewski
Roman
R