Magnetic Anisotropy of Strained La 0.7 Sr 0.3 MnO 3 Thin Films Studied by MOKE
Résumé
ABSTRACT The effects of the growth conditions and the lattice strains of pulsed laser deposited (PLD) La 0.7 Sr 0.3 MnO 3 (LSMO) thin films upon the magnetic behavior have been studied using magneto-optical Kerr effect (MOKE) at room temperature. First, the structural quality of the films was investigated by XRD and the surface morphology was studied using AFM. It is shown that both surface morphology and crystallinity are optimized when the target-to-substrate distance and the oxygen pressure are chosen in agreement with a PD 3 scaling law. Secondly, hysteresis loops have been recorded along the [100], [110] and [001] directions and the easy directions of magnetization have been determined for both stress states, i.e. tension on SrTiO 3 and compression on LaAlO 3 . In tensile films, the whole plane is found to be easy, whereas, in compressive films, the easy axis should be an intermediate direction between the film's plane and its normal. Moreover, tensile films deposited under optimized growth conditions exhibit the largest anisotropy coefficient (K 1eff = -6.9×10 5 erg/cm 3 ).