Ultrafast photoinduced phase separation dynamics in Pr_0.6Ca_0.4MnO₃ thin films

¹  Jozef Stefan Institute - Jamova 39, 1000 Ljubljana, Slovenia, EU
²  Faculty of Mathematics and Physics, University of Ljubljana - 1000 Ljubljana, Slovenia, EU
³  Laboratoire CRISMAT, CNRS UMR 6508 - Bd du Marechal Juin, F-14050 Caen Cedex, France, EU

Corresponding author: tomaz.mertelj@ijs.si

Received: 17 October 2008
Accepted: 22 May 2009

Abstract

The time-resolved magnetooptical Kerr effect in the substrate-strain-induced insulating ferromagnetic phase in (Pr_0.6Ca_0.4)MnO₃ thin films on two different substrates was measured in a magnetic field up to 1.1 T. The photoinduced Kerr rotation and ellipticity show remarkably different magnetic-field dependence. From the comparison of the magnetic-field dependences of the photoinduced and static Kerr rotation and ellipticity we conclude that a transient ferromagnetic metallic phase, embedded within the insulating ferromagnetic phase, is created upon the photoexcitation at low temperatures. A comparison of temporal dependence of the photoinduced Kerr signals with the photoinduced reflectivity indicates that the change of the fractions of the phases takes place on a timescale of ten picoseconds independent of the substrate.