Stress Induced Perpendicular Magnetic Anisotropy in FePt Thin Films

NADIA ÁLVAREZ; JAVIER GÓMEZ; A. BUTERA

Rhodes

Simposio; JEMS 2013; 2013

JEMS

FePt thin films have been broadly studied in the last years due to possible technological applications of its crystalline ordered phase. However, films grow in disordered crystalline phase (called A10) at room temperature, which presents a rich variety of magnetic phenomena. In particular, as-made films show a critical thickness above which the magnetic domains change from a planar to a stripe-like configuration. The latter is induced by a perpendicular component of the magnetic anisotropy originated by the combined effects of magnetocrystalline anisotropy (texture) and magnetoelastic energy (induced stress) [1]. We grew a series of six samples of FePt thin films with a thickness of 100 nm, varying the Ar pressure in the sputtering chamber from 3 to 13 mTorr. By this procedure it is possible to maintain an almost constant texture, but relaxing the in-plane stress. The samples were characterized by X-ray diffraction. With an AFM-MFM microscope, we have observed the transition from a striped pattern to in-plane magnetic domains for a sputtering pressure between 9 and 11 mTorr. We have also compared these images with dc magnetization and Ferromagnetic Resonance measurements. From these data we concluded that the magnetoelastic effects are the major contribution to the perpendicular anisotropy. [1] E. Sallica Leva, R. C. Valente, F. Martínez Tabares, M. Vásquez Mansilla, S. Roshdestwensky, and A. Butera, Phys. Rev. B 82, 144410 (2010).