8 research outputs found
Maximizing spin-orbit torque efficiency of Ta(O)/Py via modulating oxygen-induced interface orbital hybridization
Spin-orbit torques due to interfacial Rashba and spin Hall effects have been
widely considered as a potentially more efficient approach than the
conventional spin-transfer torque to control the magnetization of ferromagnets.
We report a comprehensive study of spin-orbit torque efficiency in
Ta(O)/Ni81Fe19 bilayers by tuning low-oxidation of \b{eta}-phase tantalum, and
find that the spin Hall angle {\theta}DL increases from ~ -0.18 of the pure
Ta/Py to the maximum value ~ -0.30 of Ta(O)/Py with 7.8% oxidation.
Furthermore, we distinguish the efficiency of the spin-orbit torque generated
by the bulk spin Hall effect and by interfacial Rashba effect, respectively,
via a series of Py/Cu(0-2 nm)/Ta(O) control experiments. The latter has more
than twofold enhancement, and even more significant than that of the former at
the optimum oxidation level. Our results indicate that 65% enhancement of the
efficiency should be related to the modulation of the interfacial Rashba-like
spin-orbit torque due to oxygen-induced orbital hybridization cross the
interface. Our results suggest that the modulation of interfacial coupling via
oxygen-induced orbital hybridization can be an alternative method to boost the
change-spin conversion rate.Comment: 15 pages, 4 figure
Thickness-dependent magnetic properties in Pt[CoNi]n multilayers with perpendicular magnetic anisotropy
We systematically investigated the Ni and Co thickness-dependent
perpendicular magnetic anisotropy (PMA) coefficient, magnetic domain
structures, and magnetization dynamics of Pt(5 nm)/[Co(t_Co nm)/Ni(t_Ni
nm)]5/Pt(1 nm) multilayers by combining the four standard magnetic
characterization techniques. The magnetic-related hysteresis loops obtained
from the field-dependent magnetization M and anomalous Hall resistivity (AHR)
\r{ho}_xy found that the two serial multilayers with t_Co = 0.2 and 0.3 nm have
the optimum PMA coefficient K_U well as the highest coercivity H_C at the Ni
thickness t_Ni = 0.6 nm. Additionally, the magnetic domain structures obtained
by Magneto-optic Kerr effect (MOKE) microscopy also significantly depend on the
thickness and K_U of the films. Furthermore, the thickness-dependent linewidth
of ferromagnetic resonance is inversely proportional to K_U and H_C, indicating
that inhomogeneous magnetic properties dominate the linewidth. However, the
intrinsic Gilbert damping constant determined by a linear fitting of
frequency-dependent linewidth does not depend on Ni thickness and K_U. Our
results could help promote the PMA [Co/Ni] multilayer applications in various
spintronic and spin-orbitronic devices.Comment: 17 pages, 4 figure