Microstructure and magnetic properties of (0 01) textured L10 FePt films on amorphous glass substrate

Abstract

L10 FePt thin films with an island-like morphology and magnetic perpendicular anisotropy were grown at low temperature (300<Tdep<375°C) by magnetron sputtering on Hoya glass substrates using a 30-nm thick Cr (200) underlayer. An MgO buffer layer with a thickness of 2nm was used to inhibit the diffusion from the Cr underlayer and promote the growth of (001) oriented L10 FePt films by inducing an in-plane lattice distortion. By varying the substrate temperature and the Ar sputter pressure (3.5<PAr<15mTorr) during the deposition, the degree of chemical order, the microstructure and the magnetic properties were tuned and the best properties in term of squareness ratio (Mr/Ms∼0.95) and coercive field (Hc∼14kOe) were observed for films deposited at Tdep=350°C and PAr=5mTorr, due to the appearance of a tensile strain, which favors the perpendicular anisotropy. The analysis of the angular dependence of remanent magnetization curves on the optimized sample suggests that the magnetization reversal is highly incoherent due to the inter-island interactions. Our results provide useful information on the low temperature growth of FePt films with perpendicular anisotropy onto glass substrates, which are relevant for a variety of technological applications, such as magnetic recording and spintronic devices.