Effect of post annealing on La0.7Sr0.3MnO3 thin films

The stability of La0.7Sr0.3MnO3 thin films fabricated by pulsed laser deposition, under different annealing procedures, was investigated. La0.7Sr0.3MnO3 films were deposited on (100) LaAlO3 substrates at 650 degrees C with the films thickness from 20 to 50 nm. The oxygen pressures used to fabricate the films were 150 mTorr and 100 mTorr. Then in situ annealing steps were performed at 100 and 150 mTorr, respectively. Curie temperatures (T-c) of the films were estimated from the peaks of the temperature dependent resistance data. For the films deposited at 100 mTorr and annealed at 150 mTorr, T-c slightly dropped for short annealing time and recovered to 360 K for 30 min annealing. For the films deposited at 100 mTorr and annealed at 150 mTorr, it maintained semiconducting behavior without transition after annealing up to 30 minutes. For ex situ post annealing, it was found that the T-c of the films strongly depended on the annealing procedures.