Magnetization reversal in patterned La0.67Sr0.33MnO3 thin films by magneto-optical Kerr imaging

Abstract

The magnetization reversal process in patterned La0.67Sr0.33MnO3 thin films has been studied at room temperature using the magneto-optical Kerr effect. The 100 and 200nm thick films were patterned into 50μm long rectangles of various widths in the 20–50μm range. In each rectangle, holes with 2 and 5μm diameters were patterned aiming at pinning the domain walls. X-ray diffraction study revealed high structural quality of both films. However, the macroscopic surface properties of both films were different, as shown by optical microscopy, which revealed cracks in the thicker film. For each thickness, both the magnetic domain images and the local magnetic hysteresis loops were recorded. For both films, the magnetization reversal process consists in nucleation and propagation of magnetic domains. In the 100nm thick film, the local hysteresis loops depend on the widths of the patterned rectangles and we observed a significant effect of the hole in pinning domains walls, leading to multiple switching transitions in the hysteresis loops. No such effect was observed inside the 200nm thick film containing cracks.