Planar Hall effect based characterization of spin orbital torques in Ta/CoFeB/MgO structures

Abstract

The spin orbital torques in Ta/CoFeB/MgO structures are experimentally investigated utilizing the planar Hall effect and magnetoresistance measurement. By angular field characterization of the planar Hall resistance at ±current, the differential resistance which is directly related to the spin orbital torques is derived. Upon curve fitting of the analytical formulas over the experimental results, it is found that the anti-damping torque, also known as spin Hall effect, is sizable while a negligible field-like torque is observed. A spin Hall angle of about 18 ± 0.6% is obtained for the Ta layer. Temperature dependent study of the spin orbital torques is also performed. It is found that temperature does not significantly modify the spin Hall angle. By cooling down the sample down to 100 K, the obtained spin Hall angle has a maximum value of about 20.5 ± 0.43%.

Influence of intermixing at the Ta/CoFeB interface on spin Hall angle in Ta/CoFeB/MgO heterostructures

“…Since available experimental data on the damping-like torque, converted to effective spin Hall angle, fluctuate between −0.03 17 and −0.11 20 , we investigate effects caused by the interface and crystallographic structure, which may be responsible for the scattering of reported data. We provide microstructural data and electrical conductivity measurements and show that both physical parameters depend on the Ta underlayer thickness, beyond the range already investigated 3 , 28 – 32 . The thinnest Ta layer is amorphous, whereas thicker Ta layers comprise the tetragonal β phase.…”

Probing Charge Density Wave Effects in 1T-TaS2 Monolayer/Ni81Fe19 Heterostructure: A Spin Dynamics Approach

“…As the current is passed through the device, an electric field is developed perpendicular to the current vector, which shows a sin­(2ϕ) dependence as depicted in Figure . Now, due to the presence of SOC material in the bilayer sample, an extra term contributes to the planar Hall effect signal, i.e., the anomalous Hall effect signal arising due to the finite tilt of the magnetization generated by the out-of-plane spin–orbit field . − Here and are the spin polarization and charge current density, respectively. The spin–orbit field depends on the SOC of the material and hence on the spin Hall effect.…”

“…The significant change in the spin−orbit fields is in contrast to the temperature-independent spin Hall angle in heavy metals. 31,38 ■ DISCUSSION AND CONCLUSIONS We have measured the magnetization, FMR, and the spin− orbit torques in the temperature region where a first-order transition between the nearly commensurate (high temperature) and commensurate (low temperature) CDW states is expected. From the temperature dependence of the magnet-ization shown in Figure 1d and the surface anisotropy field shown in Figures 3c and 3d, hysteretic loops appear in cooling/heating protocols, which is the first signature of the first-order CDW transition.…”

Observation of Planar Hall Effect in Topological Insulator -- Bi$_2$Te$_3$

“…Hence, non-magnetic materials exhibiting PHE are potential candidates for such applications since they eliminate spurious fringe field effects. PHE has been observed in a variety of systems such as ferromagnet/normal metal bilayers 11,12 , ferromagnetic semiconductors 13,14 , ferromagnetic metals 15 and topological superconductors 16,17 . Recently, the effect is in the spotlight due to its role in probing topological characteristics such as chirality.…”