Magnetic field sensors using Ce:YIG single crystals as a Faraday element

Kamada, Osamu; Higuchi, Sadao

doi:10.1109/20.951038

Cited by 8 publications

(2 citation statements)

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“…Here we derive the equations for the magnetic eigenmodes which will later be shown to approximate the optimal profile derived above. The parameters for a standard YIG sphere are given in table I [52,53], Cotton-Mouton ellipticity ΘC [21,54,55]. We assume the applied dc field Happ and the radius R based on typical experimental setup [16][17][18].…”

Section: Landau-lifshitz Equationmentioning

confidence: 99%

Optimal mode matching in cavity optomagnonics

et al. 2019

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Inelastic scattering of photons is a promising technique to manipulate magnons but it suffers from weak intrinsic coupling. We theoretically discuss an idea to increase optomagnonic coupling in optical whispering gallery mode cavities, by generalizing previous analysis to include the exchange interaction. We predict that the optomagnonic coupling constant to surface magnons in yttrium iron garnet (YIG) spheres with radius 300 µm can be up to 40 times larger than that to the macrospin Kittel mode. Whereas this enhancement falls short of the requirements for magnon manipulation in YIG, nanostructuring and/or materials with larger magneto-optical constants can bridge this gap.Magnetic insulators such as yttrium iron garnet (YIG) are promising for future spintronic applications such as low power logic devices [1], long-range information transfer [2], and quantum information [3]. Their excellent magnetic quality [4,5] implies spin waves or magnons, the excitations of the magnetic order, are long-lived. Microwaves in high quality cavities and striplines couple strongly to magnons with long (mm) wavelengths [6][7][8][9][10][11][12], i.e. the rate of energy exchange between the two systems is higher than their individual dissipation rates, but not to short wavelengths (except under special geometries [13]). Magnons can be injected electrically by metallic contacts [14,15], but only in rather small numbers. Here, we focus on the coherent coupling of magnetic order and infrared laser light with sub-µm wavelengths, that is enhanced by using the magnet as an optical cavity [16][17][18].By the high dielectric constant and almost perfect transparency in the infrared [19,20], sub-mm YIG spheres support long-living whispering gallery modes (WGMs) [16,21]. The photons, with energy deep within the band gap, scatter inelastically by absorbing or creating magnons [22,23]. This is known as Brillouin light scattering (BLS) [24], which is enhanced in an optical cavity [16-18, 21, 25-29]. These results led to predictions of the Purcell effect [30] (optically induced enhancement of magnon linewidth), magnon lasing [31] and magnon cooling [32]. However, the models addressed only the magnetostatic magnon modes, i.e. ignored retardation and the exchange interaction, with only small overlap with the WGMs [16-18, 25, 29, 33, 34]. Thus, the observed and predicted coupling rates were too low to be able to optically manipulate magnons [31,32]. Higher optomagnonic coupling can be achieved by reducing the size of the magnets down to optical wavelengths [35], but this requires nanostructuring of the magnet [36][37][38]. Coupling to magnons in a non-uniform magnetization texture is large [39]. Here, we suggest and analyze a method to increase coupling in a conventional set-up of a uniformly magnetized sub-mm YIG sphere by coupling to exchange-dipolar modes with wavelengths comparable to the WGMs.Bulk magnons in films with both exchange and dipo-lar interactions have been extensively studied [40][41][42]. In thick films, exchange reduces the life tim...

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Section: Landau-lifshitz Equationmentioning

confidence: 99%

Optimal mode matching in cavity optomagnonics

et al. 2019

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“…Until recently, much research has already been devoted to the effect of the Ce dopants on the magneto-optical properties and applications of the material [15][16][17]. However, the Ce:YIG crystal growth conditions, which significantly affect the quality of the crystal, have rarely been investigated.…”

Section: Introductionmentioning

confidence: 99%