Critical thickness for stripe domain formation in FePt thin ¯lms: dependence on residual stress

N.R. ALVAREZ; J. E. GOMEZ; A MOYA RIFFO; M. A. VICENTE ALVAREZ; A. BUTERA

JOURNAL OF APPLIED PHYSICS

AMER INST PHYSICS

Lugar: New York; Año: 2015

0021-8979

Magnetically soft FePt thin ¯lms of varying thickness (20 nm · d · 100 nm) were sputter-deposited at di®erent Ar pressures in order to systematically modify the residual stress, and hencethe magnetic anisotropy. The magnetic domain structure of FePt thin ¯lms showed a transitionfrom planar to nearly parallel stripes above a critical thickness, dcr, which was found to depend onan anisotropy contribution perpendicular to the ¯lm plane, originated essentially in magnetoelastice®ects.A careful structural characterization was made in order to obtain the strain and the stressinduced magnetic anisotropy in the samples. Vibrating sample magnetometry and magnetic forcemicroscopy were used to investigate the changes occurring in the magnetic domain structure andthe critical thickness of each set of ¯lms. Joining together structural and magnetic results we havebeen able to construct a phase diagram that divided regions of di®erent domain structures, eitherby changing the ¯lm thickness or the perpendicular magnetic anisotropy. The experimental resultscould be satisfactorily explained by using a model developed by Murayama.The observed dependence of the magnetic properties of soft FePt thin ¯lms on the fabricationconditions opens the possibility to tune the magnetic domain con¯guration from planar to stripe-like domains by changing the argon sputtering pressure used during ¯lm deposition.