Abstract
We studied spin Hall effect (SHE) in Pt100-xAux with various Au compositions x for Pt-Au/CoFeB systems by means of spin Hall magnetoresistance (SMR). We synthesized low resistive, flat, and highly (111)-textured Pt-Au alloy films by sputtering using low pressure Kr gas. We found that spin Hall angle (θSH), spin Hall conductivity (σSH), and spin diffusion length (λS) increase by alloying Pt with Au at certain x. The enhancement of σSH is consistent with the theoretically predicted increase in the intrinsic spin Hall conductivity, however quantitatively, there are some discrepancies in θSH and λS between our result and the experimental and theoretical results in the literatures 19 and 20. The discrepancy between our results and previous results would be related to the difference of the nanostructure in Pt-Au alloys related to the scattering from film surfaces and grain boundaries and the degree of phase separation in Pt-Au alloy systems.
Highlights
Current-induced spin-orbit torque (SOT) originating from the spin-Hall effect (SHE) in heavy metal/ferromagnet (HM/FM) systems has attracted attention due to their potential for application in the efficient manipulation of magnetization in nano-magnets for SOT magnetoresistive random access memory (SOT-MRAM), skyrmion and domain wall devices.1–16 For their applications, HM with high spin Hall angle |θSH| and low resistivity ρxx is necessary for an efficient SOT operation.17 An engineering to enhance an intrinsic SHE is one of possible schemes to obtain the HM
A maximum magnitude of |θSH| was observed in Pt50Au50/NiFe19 and Pt75Au25/Co20 systems using ferromagnetic resonance (FMR) and harmonic response, and the maximum magnitude of ρxx was observed at the same alloy compositions at x ∼ 50 and x ∼ 25, respectively
It is not clear why alloy compositions x at which the maximum magnitude of |θSH| was observed are different between Pt-Au/NiFe19 and Pt-Au/Co20 systems
Summary
Current-induced spin-orbit torque (SOT) originating from the spin-Hall effect (SHE) in heavy metal/ferromagnet (HM/FM) systems has attracted attention due to their potential for application in the efficient manipulation of magnetization in nano-magnets for SOT magnetoresistive random access memory (SOT-MRAM), skyrmion and domain wall devices. For their applications, HM with high spin Hall angle |θSH| and low resistivity ρxx is necessary for an efficient SOT operation. An engineering to enhance an intrinsic SHE is one of possible schemes to obtain the HM. Current-induced spin-orbit torque (SOT) originating from the spin-Hall effect (SHE) in heavy metal/ferromagnet (HM/FM) systems has attracted attention due to their potential for application in the efficient manipulation of magnetization in nano-magnets for SOT magnetoresistive random access memory (SOT-MRAM), skyrmion and domain wall devices.. Current-induced spin-orbit torque (SOT) originating from the spin-Hall effect (SHE) in heavy metal/ferromagnet (HM/FM) systems has attracted attention due to their potential for application in the efficient manipulation of magnetization in nano-magnets for SOT magnetoresistive random access memory (SOT-MRAM), skyrmion and domain wall devices.1–16 For their applications, HM with high spin Hall angle |θSH| and low resistivity ρxx is necessary for an efficient SOT operation.. A maximum magnitude of |θSH| was observed in Pt50Au50/NiFe19 and Pt75Au25/Co20 systems using ferromagnetic resonance (FMR) and harmonic response, and the maximum magnitude of ρxx was observed at the same alloy compositions at x ∼ 50 and x ∼ 25, respectively. Scitation.org/journal/adv resistivity in the prepared Pt100-xAux alloys (0 ≤ x ≤ 67) is 71.6 μΩcm, which is smaller than the previous reported results. We discuss the discrepancy of |θSH| and λS between the present experiments and the previous theoretical and experimental results in terms of the difference in the nanostructure in Pt-Au alloy
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