We demonstrate the existence of a spectrally narrow localized surface state, the so-called optical Tamm state, at the interface between one-dimensional magnetophotonic and nonmagnetic photonic crystals. The state is spectrally located inside the photonic band gaps of each of the photonic crystals comprising this magnetophotonic structure. This state is associated with a sharp transmission peak through the sample and is responsible for the substantial enhancement of the Faraday rotation for the corresponding wavelength. The experimental results are in excellent agreement with the theoretical predictions.

Thin films of polycrystalline cerium substituted yttrium iron garnet (CeYIG) were grown on an yttrium iron garnet (YIG) seed layer on Si and Si-on-insulator substrates by pulsed laser deposition, and their optical and magneto-optical properties in the near-IR region were measured. A YIG seed layer of ~30 nm thick processed by rapid thermal anneal at 800°C provided a virtual substrate to promote crystallization of the CeYIG. The effect of the thermal budget of the YIG/CeYIG growth process on the film structure, magnetic and magnetooptical properties was determined.

Photonic integrated circuits require magneto-optical (MO) materials for making nonreciprocal devices such as isolators and circulators. The most successful MO materials are rare-earth-substituted iron garnets, but these can be challenging to grow on silicon without a seed layer, which introduces spacing loss between the waveguide and the MO cladding. A pulsed-laser deposition (PLD) method is used for making MO Ce:YIG (Ce 1 Y 2 Fe 5 O 12 )/YIG (Y 3 Fe 5 O 12 ) bilayer or trilayer films on different substrates, including silicon, quartz, and Gd 3 Ga 5 O 12 (GGG), in which a multilayer film is deposited in one run and then annealed. A YIG seed layer grown above the MO Ce:YIG facilitates recrystallization during ex situ rapid thermal annealing, which results in a reduced thermal budget and simplified deposition process. A monolithically integrated optical isolator was demonstrated by direct deposition of a bilayer Ce:YIG/YIG capping layer onto a siliconon-insulator resonator. The device exhibited an insertion loss of 7.4 ± 1.8 dB and an isolation ratio of 13.0 ± 2.2 dB within the telecommunication window (λ = 1564.4 nm), which outperforms previously reported monolithic isolators.

Both polycrystalline and single-crystal films of iron-substituted strontium titanate, SrðTi 0.65 Fe 0.35 ÞO 3−δ , prepared by pulsed laser deposition, show room-temperature magnetism and Faraday rotation, with the polycrystalline films exhibiting higher saturation magnetization and Faraday rotation. The magnetic properties vary with the oxygen pressure at which the films are grown, showing a maximum at pressures of approximately 4 μ Torr at which the unit-cell volume is largest. The results are discussed in terms of the oxygen stoichiometry and corresponding Fe valence states, the structure and strain state, and the presence of small-volume fractions of metallic Fe in single-crystal films grown at the optimum deposition pressure. Integration of magneto-optical polycrystalline films on an optical-waveguide device demonstrates a nonreciprocal phase shift.

The magnetic and magneto-optic properties of epitaxial CeY 2 Fe 5 O 12 (Ce∶YIG) and Y 3 Fe 5 O 12 (yttrium iron garnet or YIG) thin films grown by pulsed laser deposition on gadolinium gallium garnet substrates are determined. An enhanced Faraday effect is known to result from Ce substitution into the yttrium iron garnet lattice, and here we characterize the magneto-optic Kerr effect, as well as the magnetic hysteresis and ferromagnetic resonance response that result from the Ce substitution. X-ray diffraction analysis reveals a high crystallographic quality for the Ce∶YIG films. Measurements of the magneto-optic Kerr effect for two different wavelengths demonstrate that the Ce∶YIG exhibits an up-to-tenfold increase in Kerr rotation compared to YIG. The Ce∶YIG has a slightly larger magnetic moment, as well as increased magnetic damping and higher magnetic anisotropy compared to YIG with a dependence on the crystalline orientation. By specific cerium substitution in YIG, our results show that the engineering of a large Kerr effect and tailored magnetic anisotropy becomes possible as required for magneto-optically active spintronic devices.

Magnonics is an emerging field dealing with ultralow power consumption logic circuits, in which the flow of spin waves, rather than electric charges, transmits and processes information. Waves, including spin waves, excel at encoding information via their phase using interference. This enables a number of inputs to be processed in one device, which offers the promise of multi-input multi-output logic gates. To realize such an integrated device, it is essential to demonstrate spin wave interferometers using spatially isotropic spin waves with high operational stability. However, spin wave reflection at the waveguide edge has previously limited the stability of interfering waves, precluding the use of isotropic spin waves, i.e., forward volume waves. Here, a spin wave absorber is demonstrated comprising a yttrium iron garnet waveguide partially covered by gold. This device is shown experimentally to be a robust spin wave interferometer using the forward volume mode, with a large ON/OFF isolation value of 13.7 dB even in magnetic fields over 30 Oe.A spin wave (SW) is a radio frequency (rf) collective excitation of the magnetic moments in a magnetic material, a magnetic counterpart of elastic waves. The transmission properties of SWs can be extensively modulated depending on the strength of the bias magnetic field, the waveguide material and the geometry 1,2 . This enables engineering of arbitrary band structures for carrier signals in the several-GHz range. These unique properties have been widely used to design passive radio frequency elements, including tunable filters 3 and delay lines 4 . However, the most important feature of SWs is their propagation without charge transport. Thus SWs have attracted attention because they offer a new paradigm for information processing in which Joule loss and its accompanying heat generation is expected to be extremely small. Therefore, SWs could be used to represent information in beyond-CMOS devices 5 . To develop logic circuits based on SWs, active control of SW flow is required. Recently, a variety of systems showing spin dynamic effects 6-12 and artificially designed structures [13][14][15][16][17][18] manipulating the local magnetic moments have been investigated. These novel systems have motivated the creation of magnonics as a research field that addresses transport, storage and processing information using SWs 19,20 . A significant feature of SWs compared to other information carriers is the usefulness of their phase information, which can be easily manipulated in logic operations. Therefore a SW interferometer is an essential component for realization of logic devices [21][22][23] . Yttrium iron garnet (YIG) is suitable for SW waveguides because of its low magnetic damping and low out-of-plane saturation magnetic field [24][25][26][27][28] . Magnons can therefore conserve their phase information over long distances in a YIG waveguide. Yu et al. recently experimentally observed SW propagation over 600 μm using a 20 nm-thick YIG waveguide with in-plane magnetization 29...

In the fifty years since the postulation of Moore’s Law, the increasing energy consumption in silicon electronics has motivated research into emerging devices. An attractive research direction is processing information via the phase of spin waves within magnonic-logic circuits, which function without charge transport and the accompanying heat generation. The functional completeness of magnonic logic circuits based on the majority function was recently proved. However, the performance of such logic circuits was rather poor due to the difficulty of controlling spin waves in the input junction of the waveguides. Here, we show how Snell’s law describes the propagation of spin waves in the junction of a Ψ-shaped magnonic majority gate composed of yttrium iron garnet with a partially metallized surface. Based on the analysis, we propose a magnonic counterpart of a core-cladding waveguide to control the wave propagation in the junction. This study has therefore experimentally demonstrated a fundamental building block of a magnonic logic circuit.

Cerium substituted yttrium iron garnet (Ce:YIG) films were grown on yttrium iron garnet (YIG) seed layers on silicon nitride films using pulsed laser deposition. Optimal process conditions for forming garnet films on silicon nitride are presented. Bulk or near-bulk magnetic and magneto-optical properties were observed for 160 nm thick Ce:YIG films grown at 640 °C on rapid thermal annealed 40 nm thick YIG grown at 640 °C and 2 Hz pulse rate. The effect of growth temperature and deposition rate on structural, magnetic and magneto-optical properties has been investigated.