  Temperature and fluence dependence of the transient photoinduced reflectivity
and the magnetooptical Kerr angle was measured in two Pr0.6Ca0.4MnO3 thin films
subject to tensile and compressive substrate-induced strain. A photoinduced
transient ferromagnetic metallic (TFM) phase is found to form below ~60K and
~40K in the substrate-strained and substrate-compressed film, respectively.
  From the hysteresis loops a difference in the TFM cluster sizes and amount of
photomodulation is observed at low temperatures and low excitation fluences in
the films with different strain. Surprisingly, the characteristic timescale for
the TFM phase photomodulation is virtually strain independent. At high
excitation fluences, the cluster sizes and amount of photomodulation are
independent on the substrate-induced strain.

Materials Science;Strongly Correlated Electrons