Effect of anisotropic strain on the charge dynamics of Nd0.5Sr0.5MnO3 thin films

We report the transmittance (T) and the pump–probe transmittance change ( Δ T ) of Nd0.5Sr0.5MnO3 (NSMO) thin films grown on SrTiO3(STO)(100) and STO(110) substrates in 1.3–1.7 eV range at room temperature. The strain of NSMO was isotropic on STO(100) and anisotropic on STO(110). Both T and Δ T showed no polarization dependence in NSMO/STO(100) but the intensity of T and Δ T was anisotropic in NSMO/STO(110). Also Δ T showed sharp exponential decay with increasing time delay between the pump and probe pulse. The short time decay behaviour ( ≲ 0.3 ps ) showed no significant polarization direction and substrate dependence, which indicates that the carrier–carrier scattering rate is not sensitive to the strain state in NSMO.