Domain nucleation and growth of La_(0.7)Ca_(0.3)MnO_(3-δ)/LaAlO_(3) films studied by low temperature magnetic force microscopy

摘要

The field-dependent domain structure of epitaxial La_(0.7)Ca_(0.3)MnO_(3-δ) thin films grown on a LaAlO_(3)(001) substrate has been studied as a function of film thickness (50 and 100 nm) and oxygen content (optimum and deficient) by means of magnetic force microscopy at 5.2 K. The epitaxially grown films show a stress induced out-of-plane anisotropy. All samples exhibit a maze type domain structure at zero field. Domain size and contrast depend on film thickness. The effect of oxygen content could not clearly been determined. Field-dependent measurements were performed by ramping a perpendicular magnetic field of up to 800 mT continuously during imaging. Domain nucleation and growth takes place by discrete reorientation of regions, which have diameters similar to the final domain width.