Abstract
Over the past few years, the study of magnetization dynamics in artificial spin ices has become a vibrant field of study. Artificial spin ices are ensembles of geometrically arranged, interacting magnetic nanoislands, which display frustration by design. These were initially created to mimic the behavior in rare earth pyrochlore materials and to study emergent behavior and frustration using two-dimensional magnetic measurement techniques. Recently, it has become clear that it is possible to create artificial spin ices, which can potentially be used as functional materials. In this perspective, we review the resonant behavior of spin ices in the GHz frequency range, focusing on their potential application as magnonic crystals. In magnonic crystals, spin waves are functionalized for logic applications by means of band structure engineering. While it has been established that artificial spin ices can possess rich mode spectra, the applicability of spin ices to create magnonic crystals hinges upon their reconfigurability. Consequently, we describe recent work aiming to develop techniques and create geometries allowing full reconfigurability of the spin ice magnetic state. We also discuss experimental, theoretical, and numerical methods for determining the spectral response of artificial spin ices and give an outlook on new directions for reconfigurable spin ices.
Highlights
Artificial spin ices are superlattices composed of interacting magnetic nanoislands placed in a geometrical arrangement.[1]
Artificial spin ices were intended as macroscopic model systems mimicking the atomic frustration in rare earth pyrochlores,[2] as well as the monopole-like excitations found in those materials,[3] with the advantage that their state could be directly measured using two-dimensional magnetic measurement techniques
Artificial spin ices evolved into superlattices designed to explore geometric frustration, free from the crystallographic constraints of pyrochlore materials
Summary
Artificial spin ices are superlattices composed of interacting magnetic nanoislands placed in a geometrical arrangement.[1]. Artificial spin ices were defined for crystallographic planes in the pyrochlores, leading to two fundamental arrangements: the square[2] and the kagome[1] lattices Despite this dimensional reduction, artificial spin ices exhibit massively degenerate ground states[1] and their energy can be minimized by magnetic field-driven and thermal relaxation protocols.[4,5,6] Building on these successes, artificial spin ices evolved into superlattices designed to explore geometric frustration, free from the crystallographic constraints of pyrochlore materials. The possibility of patterning virtually any planar geometry allows for the definition of structures exhibiting both reconfigurable magnetic states and rich magnetization dynamics For an indepth review of fabrication processes, recent developments in “connected” artificial spin ices, and prospects for artificial spin ices as frustrated superlattices, we refer the reader to recent reviews in Refs. 21 and 22
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