Magnetic domain studies of La0.7Sr0.3MnO3 film deposited on SrLaAlO3 (0 0 1) substrate

Abstract

Epitaxial 120 nm La0.7Sr0.3MnO3 (LSMO) compressively strained thin films were deposited on single-crystalline SrLaAlO3(0 0 1) (SLAO) substrates by the pulsed laser deposition (PLD) method. From the x-ray diffraction study, we confirmed that the c-axis of the LSMO crystal pointed out of the film plane. Two kinds of magnetic experiments were performed on the film: (i) the in-plane (field and the out-of-plane (field magnetic hysteresis loop measurements and (ii) magnetic force microscopy scans. We have proved from both theory and experiment that the LSMO film should exhibit the weak and tilted perpendicular magnetic anisotropy at room temperature (RT), that is, the easy axis (EA) is tilted relative to the film normal by an angle θo ≒ 37°, when the film is in the demagnetized state. The magnetic domain (MD) structure of the demagnetized LSMO film showed a maze-like pattern. Although from the in-plane hysteresis loop, HP = 600 Oe seems large enough to saturate the film, the corresponding MD structure was not in a single-domain state. Instead, there were two types of MDs: the canted MD and the saturated MD. The MD patterns of the LSMO film between the demagnetized and the remanent states were different. In addition, there were double-switch phenomena in the out-of-plane hysteresis loop. When |HN| ≅ 140 Oe, a transition of the MD pattern from the maze-like to the closure (or dense-stripe) type occurred.