13:45 〜 14:00
[26p-E201-1] [第51回講演奨励賞受賞記念講演] Origin of the background signal in spin torque ferromagnetic resonance
キーワード：スピン軌道トルク、スピン整流効果、一方向スピンホール磁気抵抗
Spin-torque ferromagnetic resonance (ST-FMR) has been widely used for estimation of the spin Hall angle (SHA) of a nonmagnetic material (NM). DC voltage, VDC, in a NM/ferromagnetic metal (FM) bilayer structure is measured under microwave irradiation. When we plot VDC as a function of external magnetic field, Bext, VDC-Bext curve is sum of symmetric and anti-symmetric Lorentzian functions around the ferromagnetic resonance (FMR) field. By analyzing this resonance curve, SHA can be quantitatively estimated.
Whereas most researches using ST-FMR have focused on the VDC-Bext curve only around the FMR condition, background (BG) signals in the ST-FMR have been neglected because it does not affect curve fitting of the resonance spectrum. We found that the BG signal is produced by the spin-dependent unidirectional spin hall magnetoresistance, origin of which is the spin Hall effect of the NM. Therefore, analysis of the BG signal also gives the value of the SHA, which enables effective crosscheck for estimation of the SHA using the ST-FMR method. We also demonstrated detection of current-induced magnetization switching in W/Co bilayer system by using the BG signal.
Whereas most researches using ST-FMR have focused on the VDC-Bext curve only around the FMR condition, background (BG) signals in the ST-FMR have been neglected because it does not affect curve fitting of the resonance spectrum. We found that the BG signal is produced by the spin-dependent unidirectional spin hall magnetoresistance, origin of which is the spin Hall effect of the NM. Therefore, analysis of the BG signal also gives the value of the SHA, which enables effective crosscheck for estimation of the SHA using the ST-FMR method. We also demonstrated detection of current-induced magnetization switching in W/Co bilayer system by using the BG signal.