Fig. 1: Nonlinear dynamics in coupled SFiM-skyrmion-based STNOs.
From: Nonlinear dynamics of directly coupled skyrmions in ferrimagnetic spin torque nano-oscillators
a Sketch of two coupled skyrmion-based STNOs. b Magnetic texture of the SFiM skyrmion. The color bar represents the z component of magnetization. c Definitions of the quantities to describe the rotational motion of the skyrmions. The blue and orange dashed circles indicate the current injection areas. d–f Fast Fourier transformation (FFT) spectra of the recorded magnetizations \({m}_{x,{{{{\rm{A}}}}}_{1}}^{{{{\rm{t}}}}}\) and \({m}_{x,{{{{\rm{A}}}}}_{2}}^{{{{\rm{t}}}}}\) averaged separately over Area1 and Area2 indicated in a, with oscillator spacing d12 = 70, 50 and 40 nm. The insets show the time evolution of magnetizations. In the calculation, we take the diameters of the circular injectors d1 = d2 = 30 nm, saturation magnetizations \({M}_{{{{\rm{s}}}}}^{{{{\rm{t}}}}}=600\) kA m−1 and \({M}_{{{{\rm{s}}}}}^{{{{\rm{b}}}}}=580\) kA m−1, and driving currents j1 = 40 MA cm−2 and j2 = 80 MA cm−2.
