Giant magnetic modulation of a planar, hybrid metamolecule resonance

Abstract

Coupling magnetic elements to metamaterial structures creates hybrid metamolecules with new opportunities. Here we report on the magnetic control of a metamolecule resonance, by utilizing the interaction between a single split ring resonator (SRR) and a magnetic thin film of permalloy. To suppress eddy current shielding, the permalloy films are patterned into arrays of 30-500 μm diameter discs. Strong hybridized resonances were observed at the anticrossing between the split ring resonance and the ferromagnetic resonance (FMR) of the permalloy. In particular, it is possible to achieve 40 dB modulation of the electric (symmetric) mode of the SRR on sweeping the applied magnetic field through the SRR/FMR anticrossing. The results open the way to the design of planar metamaterials, with potential applications in nonlinear metamaterials, tunable metamaterials and spintronics.

Expanding the Lorentz concept in magnetism

“…5 (viii) the matrix is traceless, and (ix) all other symbols possess their usual meanings. Also, note that (i) this method only works, if all the magnetic moments m k within a given monolayer are parallel to each other, and (ii) in the Lorentz limit, the dipolar sums  D xx k will give rise to the local field ( ) B r , loc as described by equations (1)- (2).…”

“…In recent years there has been growing interest into incorporating thin magnetic films (100 μm-100 nm) into metamolecules [1][2][3][4] and magnonic devices [5,6]. The properties of thin patterned magnetic films are therefore of importance.…”

“…In essence, the work presented here can be seen as an attempt to identify that shape of film (pattern) which should yield the narrowest FMR linewidth. Such experiments should have relevance in magnetic hybrid split ring resonator (SRR) metamolecules, where strong photon-magnon coupling occurs [2][3][4]. In the latter experiments, the permalloy and other magnetic films were simply patterned into small circular disks of ∼100 μm diameter, primarily to suppress eddy currents.…”

Cavity Spintronics: An Early Review of Recent Progress in the Study of Magnon–Photon Level Repulsion

“…Although the absorption of electromagnetic fields by ferromagnets in cavities had been studied for many decades before this observation, the increased filling factor, due to large, high quality samples and confined microwave fields, as well as the shift of focus from fixed to swept frequency experiments, enabled this new discovery. While initial experiments were performed at low temperatures, it was quickly realized that the experimental conditions for CMP formation could be relaxed, allowing observations at room temperature [32], in 3D microwave cavities [33,34] and using split ring resonators [35][36][37][38][39]. Although YIG, due to its ultra low damping and high spin density, continues to be the prototypical magnetic material for CMP experiments, strong coupling has also been observed in gadollinium-iron-garnet (GdIG) [40], lithium ferrite [41] and the chiral magnetic insulator Cu 2 OSeO 3 [42].…”

Hybrid Resonance Memory Metamaterial with Full‐Wave Operation

“…Various natural memory materials have been applied to implement the memory metamaterials, however, there has been no study on the memory metamaterial based on the ferromagnetic materials to the best of our knowledge. Although the metamaterial (resonator, or cavity)‐ferromagnetic hybrid systems have been studied extensively due to their distinct properties resulting from a strong resonance hybridization, the studies have been focused on the hybrid resonance occurring in a magnetically saturated state by a static external magnetic field, where the hybrid resonance disappears whenever the external magnetic field is removed.…”