scholarly journals Maximizing Spin-Orbit-Torque Efficiency of Pt/Ti Multilayers: Trade-Off Between Intrinsic Spin Hall Conductivity and Carrier Lifetime

2019 ◽  
Vol 12 (5) ◽  
Author(s):  
Lijun Zhu ◽  
R.A. Buhrman
Keyword(s):  
Carrier Lifetime ◽  
Hall Conductivity ◽  
Spin Orbit ◽  
Trade Off ◽  
Spin Hall Conductivity

scholarly journals Relation between the spin Hall conductivity and the spin Chern number for Dirac-like systems

2016 ◽  
Vol 13 (01) ◽  
pp. 1550136 ◽  
Author(s):  
Ömer F. Dayi ◽  
Elif Yunt
Keyword(s):  
Hall Effect ◽  
Chern Number ◽  
Hall Conductivity ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Quantum Level ◽  
Coupling Term ◽  
Physical Systems ◽  
Rashba Spin ◽  
Spin Hall Conductivity

A semiclassical formulation of the spin Hall effect for physical systems satisfying Dirac-like equation is introduced. We demonstrate that the main contribution to the spin Hall conductivity is given by the spin Chern number whether the spin is conserved or not at the quantum level. We illustrated the formulation within the Kane–Mele model of graphene in the absence and in the presence of the Rashba spin-orbit coupling term.

scholarly journals Spin–orbit torque engineering in β-W/CoFeB heterostructures with W–Ta or W–V alloy layers between β-W and CoFeB

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Gyu Won Kim ◽  
Do Duc Cuong ◽  
Yong Jin Kim ◽  
In Ho Cha ◽  
Taehyun Kim ◽  
...  
Keyword(s):  
Metal Layer ◽  
Spin Current ◽  
Hall Conductivity ◽  
Spin Orbit ◽  
Semiconductor Processing ◽  
Spintronic Devices ◽  
New Material ◽  
Switching Efficiency ◽  
Structure Calculations ◽  
Spin Hall Conductivity

AbstractThe spin–orbit torque (SOT) resulting from a spin current generated in a nonmagnetic transition metal layer offers a promising magnetization switching mechanism for spintronic devices. To fully exploit this mechanism, in practice, materials with high SOT efficiencies are indispensable. Moreover, new materials need to be compatible with semiconductor processing. This study introduces W–Ta and W–V alloy layers between nonmagnetic β-W and ferromagnetic CoFeB layers in β-W/CoFeB/MgO/Ta heterostructures. We carry out first-principles band structure calculations for W–Ta and W–V alloy structures to estimate the spin Hall conductivity. While the predicted spin Hall conductivity values of W–Ta alloys decrease monotonically from −0.82 × 103 S/cm for W100 at% as the Ta concentration increases, those of W–V alloys increase to −1.98 × 103 S/cm for W75V25 at% and then gradually decrease. Subsequently, we measure the spin Hall conductivities of both alloys. Experimentally, when β-W is alloyed with 20 at% V, the absolute value of the spin Hall conductivity considerably increases by 36% compared to that of the pristine β-W. We confirm that the W–V alloy also improves the SOT switching efficiency by approximately 40% compared to that of pristine β-W. This study demonstrates a new material that can act as a spin current-generating layer, leading to energy-efficient spintronic devices.

scholarly journals Quantization of spin Hall conductivity in two-dimensional topological insulators versus symmetry and spin-orbit interaction

2019 ◽  
Vol 100 (24) ◽  
Author(s):  
Filipe Matusalem ◽  
Marcelo Marques ◽  
Lara K. Teles ◽  
Lars Matthes ◽  
Jürgen Furthmüller ◽  
...  
Keyword(s):  
Topological Insulators ◽  
Orbit Interaction ◽  
Hall Conductivity ◽  
Spin Orbit ◽  
Two Dimensional ◽  
Spin Orbit Interaction ◽  
Spin Hall Conductivity

scholarly journals Giant facet-dependent spin-orbit torque and spin Hall conductivity in the triangular antiferromagnet IrMn3

2016 ◽  
Vol 2 (9) ◽  
pp. e1600759 ◽  
Author(s):  
Weifeng Zhang ◽  
Wei Han ◽  
See-Hun Yang ◽  
Yan Sun ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Spin Current ◽  
Ferromagnetic Material ◽  
Hall Conductivity ◽  
Spin Torque ◽  
Spin Orbit ◽  
Intrinsic Mechanism ◽  
Efficient Charge ◽  
Field Annealing ◽  
Experimental Findings ◽  
Spin Hall Conductivity

There has been considerable interest in spin-orbit torques for the purpose of manipulating the magnetization of ferromagnetic elements for spintronic technologies. Spin-orbit torques are derived from spin currents created from charge currents in materials with significant spin-orbit coupling that propagate into an adjacent ferromagnetic material. A key challenge is to identify materials that exhibit large spin Hall angles, that is, efficient charge-to-spin current conversion. Using spin torque ferromagnetic resonance, we report the observation of a giant spin Hall angle θSHeff of up to ~0.35 in (001)-oriented single-crystalline antiferromagnetic IrMn3 thin films, coupled to ferromagnetic permalloy layers, and a θSHeff that is about three times smaller in (111)-oriented films. For (001)-oriented samples, we show that the magnitude of θSHeff can be significantly changed by manipulating the populations of various antiferromagnetic domains through perpendicular field annealing. We identify two distinct mechanisms that contribute to θSHeff: the first mechanism, which is facet-independent, arises from conventional bulk spin-dependent scattering within the IrMn3 layer, and the second intrinsic mechanism is derived from the unconventional antiferromagnetic structure of IrMn3. Using ab initio calculations, we show that the triangular magnetic structure of IrMn3 gives rise to a substantial intrinsic spin Hall conductivity that is much larger for the (001) than for the (111) orientation, consistent with our experimental findings.

scholarly journals Variation of the giant intrinsic spin Hall conductivity of Pt with carrier lifetime

2019 ◽  
Vol 5 (7) ◽  
pp. eaav8025 ◽  
Author(s):  
Lijun Zhu ◽  
Lujun Zhu ◽  
Manling Sui ◽  
Daniel C. Ralph ◽  
Robert A. Buhrman
Keyword(s):  
Band Structure ◽  
Theoretical Prediction ◽  
Carrier Lifetime ◽  
Experimental Studies ◽  
Hall Conductivity ◽  
Rapid Variation ◽  
Clean Limit ◽  
Theoretical Predictions ◽  
Spin Hall Conductivity

More than a decade after the first theoretical and experimental studies of the spin Hall conductivity (SHC) of Pt, both its dominant origin and amplitude remain in dispute. We report the experimental determination of the rapid variation of the intrinsic SHC of Pt with the carrier lifetime (τ) in the dirty-metal regime by incorporating finely dispersed MgO intersite impurities into the Pt, while maintaining its essential band structure. This conclusively validates the theoretical prediction that the SHC in Pt in the dirty-metal regime should be dominated by the intrinsic contribution, and should decrease rapidly with shortening τ. When interfacial spin backflow is taken into account, the intrinsic SHC of Pt in the clean limit is at least 1.6 × 106 (ℏ/2e) ohm−1 m−1, more than 3.5 times greater than the available theoretical predictions. Our work also establishes a compelling spin Hall metal Pt0.6(MgO)0.4 with an internal giant spin Hall ratio of 0.73.

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