Substrate effect on the magnetic microstructure of La0.7Sr0.3MnO3 thin films studied by magnetic force microscopy

Colossal magnetoresistive ${\mathrm{La}}_{\mathrm{0.7}}{\mathrm{Sr}}_{\mathrm{0.3}}{\mathrm{MnO}}_{\mathrm{3}}$ thin films have been grown under tensile strains on $\text{(100)-}{\mathrm{SrTiO}}_{\mathrm{3}}$ substrates and compressive strains on $\text{(100)-}{\mathrm{LaAlO}}_{\mathrm{3}}$ and $\text{(110)-}{\mathrm{NdGaO}}_{\mathrm{3}}$ substrates by pulsed laser deposition. Using magnetic force microscopy (MFM), a “feather-like” magnetic pattern, characteristic of films with an in-plane magnetization, is observed for films deposited on both ${\mathrm{SrTiO}}_{\mathrm{3}}$ and ${\mathrm{NdGaO}}_{\mathrm{3}}$ while a “bubble” magnetic pattern, typical of films with an out-of-plane magnetization, is recorded for ${\mathrm{LaAlO}}_{\mathrm{3}}.$ We show that the shape of the magnetic pattern imaged by MFM is fully correlated to the easy direction of the magnetization in the film.