Current-induced resonance in long conductive ferromagnetic nano-wires

Abstract

Ferromagnetic nanowires are receiving attention as functional elements in technologically important applications in microwave devices, spintronics, and biomedicine. They can be readily fabricated over large areas using electrodeposition, and their magnetic response can be tuned through control of their size, geometry, and composition. Additionally, their geometrical properties provide a stable spin structure for manipulating magnetization dynamics using spin-polarized currents for spintronic applications. Structural analysis of individual cobalt nanowires indicated magnetocrystalline anisotropy predominantly perpendicular to the nanowire axis. This significantly alters the micromagnetic energy landscape in the nanowire and breaks the circular symmetry of the dynamic magnetization and resonance modes which is often assumed in theory. In this article, we investigate, using finite-element micromagnetic–electromagnetic simulations, the effect of the variation of magnetocrystalline anisotropy angle on the dynamic magnetization in the nanowire and leads to a shift in the resonance frequencies and modes. The resonance is induced by a pulsed electric current applied along the nanowire axis and simulations include the contributions of magnetocrystalline anisotropy, exchange, dipolar fields, and eddy currents. Understanding the magnetization dynamics induced by electric currents and spin-wave modes in metallic magnetic nanowires and their size and anisotropy angle dependence is important for the design and tuning of magnetic nanowire arrays and devices.