Spin-orbit-torque driven magnetoimpedance in Pt-layer/magnetic-ribbon heterostructures

چکیده مقاله

When a flow of electrons passes through a paramagnetic layer with strong spin-orbit-coupling such
as platinum (Pt), a net spin current is produced via the spin Hall effect (SHE). This spin current can
exert a torque on the magnetization of an adjacent ferromagnetic layer which can be probed via
magnetization dynamic responses, e.g., spin-torque ferromagnetic resonance. Nevertheless, that
effect in the lower frequency magnetization dynamic regime where the skin effect occurs in high
permeability ferromagnetic conductors, namely, the magneto-impedance (MI) effect, can be fundamentally
important, and has not been studied so far. Here, by utilizing the MI effect in the
magnetic-ribbon/Pt heterostructure with high transvers magnetic permeability that allows the ac
current effectively confined at the skin depth of 100 nm thickness, the effect of spin-orbit-torque
(SOT) induced by the SHE probed via the MI measurement is investigated. We observed a systematic
MI frequency shift that increases by increasing the applied current amplitude and thickness of
the Pt layer (varying from 0 nm to 20 nm). In addition, the role of the Pt layer in the ribbon/Pt heterostructure
is evaluated with the ferromagnetic resonance effect representing a standard Gilbert
damping increase as a result of the presence of the SHE. Our results unveil the role of SOT in
dynamic control of the transverse magnetic permeability probed by impedance spectroscopy as a
useful and valuable technique for detection of future SHE devices.