Optimization of La_0.7Sr_0.3MnO₃ thin film by pulsed laser deposition for spin injection

We have investigated low temperature magnetic properties of La_0.7Sr_0.3MnO₃ (LSMO) thin films on SrTiO₃ (STO) substrate deposited by pulsed laser deposition (PLD). We observed a large change in the Curie temperature T_C when the LSMO film thickness is reduced from 4 nm (T_C∼280 K) to 2 nm (T_C ∼100 K), which is a result of high strain present at the STO–LSMO interface. The presence of the strain is confirmed by a grazing angle X-ray diffraction (XRD) technique where a particular peak is shifted away from the bulk peak position as we decrease the thickness. In a LSMO/Pb[Zr_yTi_1−y]O₃ (PZT)/LSMO magnetic tunnel junction (MTJ), these LSMO thin films can be used for spin injection into the tunnel barrier. Here spin current can be manipulated by changing the strain present at the LSMO–PZT interface by using piezoelectric properties of PZT