Ferromagnetic Resonance Properties and Anisotropy of Ni-Mn-Ga Thin Films of Different Thicknesses Deposited on Si Substrate

Ni-Mn-Ga films of different thicknesses were deposited onto Si(100) substrates by magnetron sputtering and annealed at 1073 K for 1 h in high vacuum. X-ray diffraction analysis showed the formation of 220 fiber texture perpendicular to the film plane. Magnetic properties of thin films were investigated at room temperature using ferromagnetic resonance (FMR) technique. The dependencies of both the FMR absorption maximum position and resonance linewidth on the direction of the external magnetic field with respect to the film normal were studied. The data analysis showed that the direction of magnetocrystalline anisotropy easy axis in the films makes 45° angle with the film normal. The modeling allowed evaluation of the uniaxial anisotropy constant, which is found to increase with thickness of Ni-Mn-Ga films. Uniaxial anisotropy constants were found to be ∼2.8×105 erg/cm3 for 0.1 and 0.5 μm film thickness, ∼4.2×105 erg/cm3 for 1 μm film, and ∼5.1×105 erg/cm3 for 3 μm film.