Dynamic response of an artificial square spin ice

TL;DR

This study investigates the magnetization dynamics of an artificial square spin-ice lattice made of Ni80Fe20 using broadband ferromagnetic resonance spectroscopy, revealing complex mode spectra related to different magnetization states and hysteretic behavior.

Contribution

It demonstrates that resonance experiments can identify spin-ice states and provides a semi-analytical model linking magnetization states to observed spectra in artificial frustrated magnetic systems.

Findings

Rich spectrum of modes corresponding to various magnetization states

Hysteretic behavior observed below 400 Oe

Micromagnetic simulations explain the origin of spectra

Abstract

Magnetization dynamics in an artificial square spin-ice lattice made of Ni80Fe20 with magnetic field applied in the lattice plane is investigated by broadband ferromagnetic resonance spectroscopy. The experimentally observed dispersion shows a rich spectrum of modes corresponding to different magnetization states. These magnetization states are determined by exchange and dipolar interaction between individual islands, as is confirmed by a semianalytical model. In the low field regime below 400 Oe a hysteretic behavior in the mode spectrum is found. Micromagnetic simulations reveal that the origin of the observed spectra is due to the initialization of different magnetization states of individual nanomagnets. Our results indicate that it might be possible to determine the spin-ice state by resonance experiments and are a first step towards the understanding of artificial geometrically frustrated magnetic systems in the high-frequency regime.