Voltage-Controlled Ferromagnetic Resonance of Dipole-Coupled Co40Fe40B20 Nanoellipses

Multiuse or reconfigurable rf front ends require rf filters capable of dynamically broadening and/or shifting their operating frequency. Utilizing frequency-agile filters, the burden of signal processing is shifted from application specific hardware (e.g., application specific integrated circuit) to software-based solutions such as software defined radio (SDR). Current filter tuning approaches electrically modify surface or bulk acoustic wave signal absorption, but typically require prohibitively large electric fields to achieve large tuning. Alternatively, multiferroic based approaches overcome this limitation by leveraging magnetoelasticity to tune the ferromagnetic resonance (FMR) of nanostructures. Four configurations of Co40Fe40B20 nanoellipses are simulated to theoretically demonstrate how voltage-induced strain and dipole-coupling affect their FMR spectra. For a single ellipse, two FMR peaks are observed, signifying primary (bulk) and secondary (edge) modes that were shifted up to approximately 2 GHz by a voltage-induced strain. For dipole-coupled ellipses, a third resonance peak develops in addition to the bulk and edge modes and similar frequency shifting is observed with equal strain applied to both nanostructures. When strain is applied to only one ellipse, fourth and fifth resonance peaks develop. The results demonstrate the high tunability of magnetoelastic based designs for future strain-based filtering, antennas, or computing applications.