High-quality thulium iron garnet films with tunable perpendicular magnetic anisotropy by off-axis sputtering ??correlation between magnetic properties and film strain
Journal
Scientific Reports
Journal Volume
8
Journal Issue
1
Date Issued
2018
Author(s)
Wu, C.N.
Tseng, C.C.
Fanchiang, Y.T.
Cheng, C.K.
Lin, K.Y.
Yeh, S.L.
Yang, S.R.
Wu, C.T.
Liu, T.
Wu, M.
Kwo, J.
Abstract
AbstractThulium iron garnet (TmIG) films with perpendicular magnetic anisotropy (PMA) were grown on gadolinium gallium garnet (GGG) (111) substrates by off-axis sputtering. High-resolution synchrotron radiation X-ray diffraction studies and spherical aberration-corrected scanning transmission electron microscope (Cs-corrected STEM) images showed the excellent crystallinity of the films and their sharp interface with GGG. Damping constant of TmIG thin film was determined to be 0.0133 by frequency-dependent ferromagnetic resonance (FMR) measurements. The saturation magnetization (Ms) and the coercive field (Hc) were obtained systematically as a function of the longitudinal distance (L) between the sputtering target and the substrate. A 170% enhancement of PMA field (H��) was achieved by tuning the film composition to increase the tensile strain. Moreover, current-induced magnetization switching on a Pt/TmIG structure was demonstrated with an ultra-low critical current density (jc) of 2.5?��?106?A/cm2, an order of magnitude smaller than the previously reported value. We were able to tune Ms, Hc and H�� to obtain an ultra-low jc of switching the magnetization, showing the great potential of sputtered TmIG films for spintronics.
Type
journal article