Ultrafast optical probes of dynamic behavior in La0.7Sr0.3MnO3/YBa2Cu3O7-δ/La0.7Sr0.3MnO3 heterostructure
L. Peng, Ch. Cai+, D. H. Xu, Y. Liu
Department of Physics, Shanghai University of Electric Power, 201300 Shanghai, China
+Department of Physics, Shanghai University, 200444 Shanghai, China
Abstract
Ultrafast pump-optical probe spectroscopy was used to analyze
carriers dynamics behavior in
La0.7Sr0.3MnO3/YBa2Cu3O7-δ/La0.7Sr0.3MnO3 heterostructure.
Our results
show the pump signal Δ R/R for higher laser power
(such as 21 and 41 mW),
below Tc, first goes positive, then crosses zero and goes negative, before relaxing back
to equilibrium over a time scale of a few ten picoseconds. We extract the characteristic
relaxation time of the different process by fitting the data at these powers with a
three-exponential decay. For higher laser power, the long characteristic relaxation time
are obtained, which implies the competition between FM order and SC order in the
La0.7Sr0.3MnO3/YBa2Cu3O7-δ/La0.7Sr0.3MnO3 heterostructure.