Reconfigurable magnonic mode-hybridisation and spectral control in a bicomponent artificial spin ice

Abstract

Strongly-interacting nanomagnetic arrays are finding increasing use as model host systems for reconfigurable magnonics. The strong inter-element coupling allows for stark spectral differences across a broad microstate space due to shifts in the dipolar field landscape. While these systems have yielded impressive initial results, developing rapid, scaleable means to access a broad range of spectrally-distinct microstates is an open research problem. We present a scheme whereby square artificial spin ice is modified by widening a ‘staircase’ subset of bars relative to the rest of the array, allowing preparation of any ordered vertex state via simple global-field protocols. Available microstates range from the system ground-state to high-energy ‘monopole’ states, with rich and distinct microstate-specific magnon spectra observed. Microstate-dependent mode-hybridisation and anticrossings are observed at both remanence and in-field with dynamic coupling strength tunable via microstate-selection. Experimental coupling strengths are found up to g/2π = 0.16 GHz. Microstate control allows fine mode-frequency shifting, gap creation and closing, and active mode number selection.

Spectral fingerprinting: microstate readout via remanence ferromagnetic resonance in artificial spin ice

“…WM-S and WM-HDS samples, shown in figures 1(b) and (c) are square ASI with sublattices of wide (w 1 ) and thin (w 2 ) bars. Wider bars have lower coercivity (H c1 < H c2 ), allowing microstate control via the application of global field [19].…”

“…The precise microstate imprints subtle, informative details on the spin-wave spectra. However, these spectral shifts are dwarfed by mode frequency jumps associated with island reversal (∼2 GHz vs 0.2 GHz) [19], limiting the microstate information revealed by field swept FMR.…”

Writable spin wave nanochannels in an artificial-spin-ice-mediated ferromagnetic thin film

“…The significantly different responses between vertical and horizontal domain states are indicative of a perfect reconfigurable magnonic crystal, in which the spin wave transmission can be conveniently switched on and/or off by tuning the magnetic configurations of the top ASIs. The spectra excited by in-plane microwave can be conveniently realized by patterning samples on top of a coplanar waveguide (CPW) 24-27, 30 or mounting samples on a CPW chip with a flip-chip technique in broadband ferromagnetic resonance (FMR) experiments 29 . Thus, our proposed reconfigurable magnonic crystal with tunable magnonic spectra could be directly realized by FMR measurements.…”

Spin wave excitation and directional propagation in presence of magnetic charges in square artificial spin ice

“…In order to acquire this ability, fundamental and in-depth understanding of the behavior of SWs in magnetic materials of different nanoscale geometries is very important. Recently a few experimental as well as theoretical results on the investigation of this aspect of SWs have been reported in literature [21][22][23][24][25][26]. The magnetic nanostructures, which are involved in the propagation of SWs, may in general interact via long range dipolar interactions.…”