Fig. 2: Voltage-dependent ST-FMR spectra.
From: Voltage-driven gigahertz frequency tuning of spin Hall nano-oscillators
a ST-FMR spectra of the Co/Ni sample for sequentially applied gate voltages (initial, +5 V, and −5 V). Here, the microwave frequency is 15 GHz. The dotted lines are the best fits based on Eq. (1). b Resonance frequency (\({f}_{{{{{{\rm{res}}}}}},z}\)) as a function of resonance field \({B}_{{{{{{\rm{res}}}}}},z}\) of the sample with different sequentially applied gate voltages. c Variation of perpendicular magnetic anisotropy field (\({B}_{{{{{{\rm{k}}}}}}}\)) versus sequentially applied gate voltage, where the error bars are due to the uncertainty in fitting the data in Fig. 2b to the Kittel formula, \({f}_{{{{{{\rm{res}}}}}},z}=\frac{\gamma }{2\pi }({B}_{{{{{{\rm{res}}}}}},z}+{B}_{{{{{{\rm{k}}}}}}})\). d The linewidth of the Lorentzian function (\(\triangle B\)) as a function of the \({f}_{{{{{{\rm{res}}}}}},{{{{{\rm{z}}}}}}}\) of the sample with sequentially applied gate voltages. e Variation of effective damping constant (\({\alpha }_{{{{{{\rm{eff}}}}}}}\)) versus sequentially applied gate voltage, where the error bars are due to the uncertainty in fitting the data in Fig. 2d to the equation, \(\triangle B=\triangle {B}_{0}+\frac{2\pi {\alpha }_{{{{{{\rm{eff}}}}}}}}{\gamma }{f}_{{{{{{\rm{res}}}}}},z}\).
