Self-supported vortex texture in 3D curved magnets

Abstract

Magnetic textures in the self-supported nanostructure, such as vortex, are promising for magnetic hyperthermia therapy and spintronics due to their low remanent state and topological protection. These configurations emerge from energy minimization in confined systems, such as nanodisk or nanoparticles. There are many techniques used to confine these magnetic textures. However, the most robust, cheap, and reproducible is always sought. This work applies colloidal lithography to produce self-supported nanocaps with a vortex as the ground state. Firstly, we perform micromagnetic simulations to determine which diameters and thicknesses stabilize the vortex as a ground state on nanocaps. Secondly, we simulate the magnetization curves to find the conditions with the smallest remanent state and largest loop hysteresis curves area. Finally, we experimentally corroborate the vortex configuration ground state using electron holography and vibrating the sample magnetometer. In addition, we performed a dynamic simulation to investigate the gyrotropic modes of the vortex core. We present a concise route to the fabrication of scalable vortex magnetic nanocaps. Our results show that the magnetic nanocaps produced have a great potential for application in medicine, such as magnetic hyperthermia, and in spintronics, for spin-transfer torque nano-oscillators.