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[18a-D104-3] Direct-current modulation in spin torque ferromagnetic resonance spectra
in permalloy/Pt bilayer films
Keywords:spintronics, ST-FMR
Spin Hall effect is the conversion phenomenon from charge to spin currents in heavy metals due to the spin orbit interaction, and the conversion efficiency is called the spin Hall angle. It can be characterized by ferromagnetic resonance in ferromagnetic (FM)/heavy metal (HM) bilayer films, namely spin torque ferromagnetic resonance (ST-FMR) measurements.
In ST-FMR measurements in FM/HM bilayer films, there have been two evaluation methods utilized, namely the spectrum intensity ratio (SIR) and the effective damping modulation (EDM) methods proposed by Liu et al. in 2011 [1]. In the SIR method, the intensity ratio between symmetric and asymmetric components of the ST-FMR spectrum gives spin Hall angle, while in the EDM method the degree of the damping modulation with respect to direct current (DC) density in HM is proportional to the spin Hall angle [2, 3]. So far, these two methods have been used complementarily; however, it appears that the phenomenon of EDM has been little understood. In this study, we examined the DC effect on ST-FMR spectra [4].
References
[1] L. Liu et al., Phys. Rev. Lett. 106, 036601 (2011).
[2] K. Kondou et al., Appl. Phys. Express 5, 073002 (2012).
[3] S. Kasai et al., Appl. Phys. Lett. 104, 092408 (2014).
[4] S. Hirayama et al., Appl. Phys. Express 11, 013002 (2018)
In ST-FMR measurements in FM/HM bilayer films, there have been two evaluation methods utilized, namely the spectrum intensity ratio (SIR) and the effective damping modulation (EDM) methods proposed by Liu et al. in 2011 [1]. In the SIR method, the intensity ratio between symmetric and asymmetric components of the ST-FMR spectrum gives spin Hall angle, while in the EDM method the degree of the damping modulation with respect to direct current (DC) density in HM is proportional to the spin Hall angle [2, 3]. So far, these two methods have been used complementarily; however, it appears that the phenomenon of EDM has been little understood. In this study, we examined the DC effect on ST-FMR spectra [4].
References
[1] L. Liu et al., Phys. Rev. Lett. 106, 036601 (2011).
[2] K. Kondou et al., Appl. Phys. Express 5, 073002 (2012).
[3] S. Kasai et al., Appl. Phys. Lett. 104, 092408 (2014).
[4] S. Hirayama et al., Appl. Phys. Express 11, 013002 (2018)