Dissipative Magnetic Breathers Induced by Time-Modulated Voltages

During the last years, there has been a growing interest in the coupling between voltages and the magnetization of insulating nanostructures. Applied voltages can change the magnetic anisotropy of magnetic tunnel junctions and generate magnetization dynamics more efficiently than alternating magnetic fields and spin-polarized electric currents because it avoids the Joule dissipation. Here, we study the formation of dissipative breathers in nanomagnets forced by an oscillatory voltage. The breathers are localized states with an oscillatory envelope. The voltage frequency is close to twice the ferromagnetic resonance frequency. Numerical simulations reveal that the breathers can emit evanescent spin waves from their center in a dipolarlike shape when the voltage is above a certain threshold. Based on an amplitude equation, we explain the existence and behavior of these voltage-induced breathing solitons, while the anisotropic spin-wave emission corresponds to a spontaneous symmetry-breaking instability. © 2018 American Physical Society.