Publisher’s Note: “Origin of spin–orbit torque in single-layer CoFeB investigated via in-plane harmonic Hall measurements” [AIP Advances 11, 025033 (2021)]
We investigate the Pt thickness dependence of spin–orbit torques (SOTs) in Co/Pt layers grown on ... more We investigate the Pt thickness dependence of spin–orbit torques (SOTs) in Co/Pt layers grown on single crystalline SrTiO3 and LaAlO3 and amorphous SiO2 substrates. We measure the SOT-induced effective damping-like fields and spin Hall magnetoresistances of the Co/Pt (tPt) samples, where tPt varies from 0.5 to 5.5 nm. We find that the Co/Pt layers grown on the single crystalline substrates show weaker thickness dependence of the SOT than the samples on the SiO2 substrate, which cannot be explained by the conventional bulk spin Hall effect in the Pt layer. This indicates that there is a non-negligible interfacial SOT originating from the Pt/substrate interface, which is more pronounced for thinner Pt. These results provide a way to design SOT material structures with enhanced SOT efficiency by incorporating interfacial SOT.
We demonstrate that the spin Hall magnetoresistance (SMR) of epitaxial Pt/Co bilayers on MgO(110)... more We demonstrate that the spin Hall magnetoresistance (SMR) of epitaxial Pt/Co bilayers on MgO(110) single crystal substrates is strongly anisotropic and depends on the applied current direction with respect to the two primary in-plane crystal directions [001] and [1 10], in the Pt layer. SMR results at different temperatures qualitatively suggest the D'yakonov-Perel spin relaxation mechanism through the invariance of the spin diffusion length λ s f for a given current direction, while also suggesting an anisotropic Rashba-Edelstein effect from the ratio of λ [001] s f to λ [1 10] s f . Finally, deviation from the standard SMR model spurs the need for new theory that properly characterizes and quantifies the anisotropies in such epitaxial systems.
Controlling magnetism with electric field directly or through strain-driven piezoelectric couplin... more Controlling magnetism with electric field directly or through strain-driven piezoelectric coupling remains a key goal of spintronics. Here we demonstrate that giant piezomagnetism, a linear magneto-mechanic coupling effect, is manifest in antiperovskite Mn3NiN, facilitated by its geometrically frustrated antiferromagnetism opening the possibility of new memory device concepts. Films of Mn3NiN with intrinsic biaxial strains of ±0.25% result in Néel transition shifts up to 60K and magnetisation changes consistent with theory. Films grown on BaTiO3 display a striking magnetisation jump in response to uniaxial strain from the intrinsic BaTiO3 structural transition, with an inferred 44% strain coupling efficiency and a magnetoelectric coefficient α (where α=dB/dE) of 0.018 G cm/V. The latter agrees with the 1000-fold increase over Cr2O3 predicted by theory. Overall our observations pave the way for further research into the broader family of Mn-based antiperovskites where yet larger piez...
Publisher’s Note: “Origin of spin–orbit torque in single-layer CoFeB investigated via in-plane harmonic Hall measurements” [AIP Advances 11, 025033 (2021)]
We investigate the Pt thickness dependence of spin–orbit torques (SOTs) in Co/Pt layers grown on ... more We investigate the Pt thickness dependence of spin–orbit torques (SOTs) in Co/Pt layers grown on single crystalline SrTiO3 and LaAlO3 and amorphous SiO2 substrates. We measure the SOT-induced effective damping-like fields and spin Hall magnetoresistances of the Co/Pt (tPt) samples, where tPt varies from 0.5 to 5.5 nm. We find that the Co/Pt layers grown on the single crystalline substrates show weaker thickness dependence of the SOT than the samples on the SiO2 substrate, which cannot be explained by the conventional bulk spin Hall effect in the Pt layer. This indicates that there is a non-negligible interfacial SOT originating from the Pt/substrate interface, which is more pronounced for thinner Pt. These results provide a way to design SOT material structures with enhanced SOT efficiency by incorporating interfacial SOT.
We demonstrate that the spin Hall magnetoresistance (SMR) of epitaxial Pt/Co bilayers on MgO(110)... more We demonstrate that the spin Hall magnetoresistance (SMR) of epitaxial Pt/Co bilayers on MgO(110) single crystal substrates is strongly anisotropic and depends on the applied current direction with respect to the two primary in-plane crystal directions [001] and [1 10], in the Pt layer. SMR results at different temperatures qualitatively suggest the D'yakonov-Perel spin relaxation mechanism through the invariance of the spin diffusion length λ s f for a given current direction, while also suggesting an anisotropic Rashba-Edelstein effect from the ratio of λ [001] s f to λ [1 10] s f . Finally, deviation from the standard SMR model spurs the need for new theory that properly characterizes and quantifies the anisotropies in such epitaxial systems.
Controlling magnetism with electric field directly or through strain-driven piezoelectric couplin... more Controlling magnetism with electric field directly or through strain-driven piezoelectric coupling remains a key goal of spintronics. Here we demonstrate that giant piezomagnetism, a linear magneto-mechanic coupling effect, is manifest in antiperovskite Mn3NiN, facilitated by its geometrically frustrated antiferromagnetism opening the possibility of new memory device concepts. Films of Mn3NiN with intrinsic biaxial strains of ±0.25% result in Néel transition shifts up to 60K and magnetisation changes consistent with theory. Films grown on BaTiO3 display a striking magnetisation jump in response to uniaxial strain from the intrinsic BaTiO3 structural transition, with an inferred 44% strain coupling efficiency and a magnetoelectric coefficient α (where α=dB/dE) of 0.018 G cm/V. The latter agrees with the 1000-fold increase over Cr2O3 predicted by theory. Overall our observations pave the way for further research into the broader family of Mn-based antiperovskites where yet larger piez...
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Papers by Ryan Thompson