Universal method for separating spin pumping from spin rectification voltage of ferromagnetic resonance

Area of Science:

• Spintronics
• Condensed Matter Physics
• Materials Science

Background:

• Separating spin pumping and spin rectification signals is crucial for spintronics research.
• Existing methods are often device-specific, hindering universal quantification of the spin Hall angle.
• Ferromagnetic resonance (FMR) is a key technique for studying spin dynamics.

Purpose of the Study:

• To develop a universal method for distinguishing spin pumping from spin rectification signals in bilayer spintronics devices.
• To enable accurate and device-independent quantification of the spin Hall angle via FMR.
• To facilitate direct measurement of the nonlinear spin current evolution.

Main Methods:

• Utilizing the distinct angular and field symmetries of spin pumping and spin rectification signals.
• Applying the method to analyze charge voltages in bilayers induced by FMR.
• Independent of specific FMR line shape characteristics.

Main Results:

• A universal method for separating spin pumping and spin rectification signals was successfully developed.
• The method overcomes limitations imposed by device-specific microwave properties.
• The spin Hall angle in a Py/Pt bilayer was directly measured as 0.021±0.015 for large precession angles (~20°).

Conclusions:

• The developed method provides a universal approach to analyze spintronics devices.
• It resolves the long-standing issue of signal separation in bilayers.
• This work enables direct measurement of spin current nonlinear evolution and accurate spin Hall angle quantification.