A. Sposito

Magnetic control of a meta-molecule

Metamaterials offer the prospect of new science and applications. They have been designed by shaping or changing the material of the individual meta-molecules to achieve properties not naturally attainable. Composite meta-molecules incorporating a magnetic component offer new opportunities. In this work we report on the interaction between a non-magnetic split ring resonator (SRR) and a thin film of yttrium iron garnet (YIG). Strong hybridized resonances are observed. While the SRR is characterized by a magnetic and electric resonance, in practice, it is found that the YIG couples strongly to this symmetric (electric) mode of the SRR. It is also demonstrated that the anti-crossing region provides fertile ground for the creation of elementary excitations such as backward volume magnetostatic waves.

Pulsed laser deposition of high-quality µm-thick YIG films on YAG

We report the epitaxial growth of high-quality µm-thick yttrium iron garnet (YIG) films on yttrium aluminium garnet (YAG) substrates by pulsed laser deposition (PLD). The effects of substrate temperature and oxygen pressure on composition, crystallinity, optical transmission and ferromagnetic resonance (FMR) linewidth have been investigated. An FMR linewidth as low as 1.75 mT at 6 GHz was achieved by depositing YIG on YAG substrates with (100) orientation at a substrate temperature of ~1600 K and with oxygen pressure of ~1 Pa.

Combinatorial pulsed laser deposition of doped yttrium iron garnet films on yttrium aluminium garnet

We investigate the crystalline growth of yttrium iron garnet (YIG) films doped with bismuth (Bi) and cerium (Ce) by combinatorial pulsed laser deposition, co-ablating a YIG target and either a Bi2O3 or a CeO2 target, for applications in microwave and optical communications. Substrate temperature is critical for crystalline growth of YIG with simultaneous inclusion of Bi in the garnet lattice, whereas Ce is not incorporated in the garnet structure, but forms a separate CeO2 phase.

Laser-Induced Forward Transfer-printing of focused ion beam pre-machined crystalline magneto-optic yttrium iron garnet micro-discs.

We present femtosecond laser-induced forward transfer of focused ion beam pre-machined discs of crystalline magneto-optic yttrium iron garnet (YIG) films. Debris-free circular micro-discs with smooth edges and surface uniformity have been successfully printed. The crystalline nature of the printed micro-discs has not been altered by the LIFT printing process, as was confirmed via micro-Raman measurements.

Multi-beam pulsed laser deposition for advanced thin-film optical waveguides

We discuss our progress in the use of multiple laser beams and multiple targets for the pulsed laser deposition of thin films for waveguide laser and magneto-optic applications. In contrast to the more widely used single-beam/single-target geometries, having more than one laser-produced plume can allow tuning of the material properties and complex engineering of the deposited thin films. For optical applications - the majority of the work reported here - dopants can be selectively introduced, lattice mismatch and residual strain can be compensated, which is an important factor for successful growth of thin films of ~ tens of microns thickness, and refractive index values can be adjusted for fabrication of sophisticated waveguiding structures. We discuss mixed, layered, superlattice and Bragg reflector growth, which involve out-of-plane engineering of the film structure, and in-plane engineered geometries for designs relevant to thin-film disc lasing devices. Finally we briefly discuss our most recent use of multi-plume growth for magneto-optic thin films, which involves compositional tuning of final magnetic properties.

Selective growth of yttrium iron garnet and yttrium ferrite by combinatorial pulsed-laser ablation of common precursors

In this paper, we demonstrate the capability of growing two alternative complex oxides with different stoichiometries and crystal structures, by choosing the appropriate substrate and adjusting the target ablation ratio, and tuning their composition and properties by combinatorial pulsed-laser ablation of their precursors. In particular, we successfully grew epitaxial crystalline yttrium iron garnet (Y3Fe5O12) on yttrium aluminium garnet (Y3Al5O12) substrates and polycrystalline yttrium ferrite (YFeO3) on sapphire (α-Al2O3) substrates by co-ablation of yttrium oxide and iron oxide targets.

Laser-induced forward transfer-printing of pre-machined crystalline magneto-optic garnet discs

We present femtosecond laser-induced forward transfer of focussed ion beam pre-machined crystalline magneto-optic Yttrium Iron Garnet films. Debris-free circular micro-discs with smooth edges and surface uniformity have been successfully printed.

Emerging pulsed laser deposition techniques

The use of lasers for the deposition and processing of electronic and photonic materials is becoming increasingly widespread and advances in processing technology are reducing costs and increasing throughput. Laser deposition of photonic materials and laser processing techniques can produce high quality devices with novel properties. Part one covers laser deposition and growth of materials, including pulsed laser deposition and laser-induced self-assembly of semiconductors. Part two describes laser patterning and lithography techniques, such as 3D laser lithography. Part three looks at laser treatments to manipulate properties of photonic materials for applications such as optical storage, laser components, waveguides and displays.