5 research outputs found
Spin-orbit torque in Cr/CoFeAl/MgO and Ru/CoFeAl/MgO epitaxial magnetic heterostructures
Full text linkWe study the spin-orbit torque (SOT) effective fields in Cr/CoFeAl/MgO and
Ru/CoFeAl/MgO magnetic heterostructures using the adiabatic harmonic Hall
measurement. High-quality perpendicular-magnetic-anisotropy CoFeAl layers were
grown on Cr and Ru layers. The magnitudes of the SOT effective fields were
found to significantly depend on the underlayer material (Cr or Ru) as well as
their thicknesses. The damping-like longitudinal effective field ({\Delta}H_L)
increases with increasing underlayer thickness for all heterostructures. In
contrast, the field-like transverse effective field ({\Delta}H_T) increases
with increasing Ru thickness while it is almost constant or slightly decreases
with increasing Cr thickness. The sign of {\Delta}H_L observed in the
Cr-underlayer devices is opposite from that in the Ru-underlayer devices while
{\Delta}H_T shows the same sign with a small magnitude. The opposite directions
of {\Delta}HL indicate that the signs of spin Hall angle in Cr and Ru are
opposite, which are in good agreement with theoretical predictions. These
results show sizable contribution from SOT even for elements with small spin
orbit coupling such as 3d Cr and 4d Ru.Comment: 10 pages, 5 figures, AIP Advances 201
