We have investigated recrystallization of amorphous Yttrium Iron Garnet (YIG) by annealing in oxygen atmosphere. Our findings show that well below the melting temperature the material transforms into a fully epitaxial layer with exceptional quality, both structural and magnetic. In ferromagnetic resonance (FMR) ultra low damping and extremely narrow linewidth can be observed. For a 56 nm thick layer a damping constant of α = (6.15 ± 1.50) · 10−5 is found and the linewidth at 9.6 GHz is as small as 1.30 ± 0.05 Oe which are the lowest values for PLD grown thin films reported so far. Even for a 20 nm thick layer a damping constant of α = (7.35 ± 1.40) · 10−5 is found which is the lowest value for ultrathin films published so far. The FMR linewidth in this case is 3.49 ± 0.10 Oe at 9.6 GHz. Our results not only present a method of depositing thin film YIG of unprecedented quality but also open up new options for the fabrication of thin film complex oxides or even other crystalline materials.

We report combined experimental and theoretical investigations of x-ray absorption at the Ru-L 2,3 and O-K thresholds of the Ru͑IV͒ compounds RuO 2 and Sr 2 RuO 4 and of the Ru͑V͒ compound Sr 4 Ru 2 O 9 . Significant differences in the intensity distribution of the t 2g -related and e g -related peaks between the L 3 and the L 2 edges are found, due to the combined effects of 4d spin-orbit coupling and the interelectronic Coulomb interaction described by the Slater integrals. The observed spectral features can be well reproduced by crystal-fieldmultiplet calculations. With increasing the Ru valence from IV to V, the spectra are shifted by Х1.5 eV to higher energy at the Ru-L 2,3 edges and Х1.0 eV to lower energy at the O-K edge, which is of the same order of magnitude as on going from the divalent to the trivalent late 3d transition-metal oxides.

Nano resonators in which mechanical vibrations and spin waves can be coupled are an intriguing concept that can be used in quantum information processing to transfer information between different states of excitation. Until now, the fabrication of free standing magnetic nanostructures which host long lived spin wave excitatons and may be suitable as mechanical resonators seemed elusive. We demonstrate the fabrication of free standing monocrystalline yttrium iron garnet (YIG) 3D nanoresonators with nearly ideal magnetic properties. The freestanding 3D structures are obtained using a complex lithography process including room temperature deposition and liftoff of amorphous YIG and subsequent crystallization by annealing. The crystallization nucleates from the substrate and propagates across the structure even around bends over distances of several micrometers to form e.g. monocrystalline resonators as shown by transmission electron microscopy. Spin wave excitations in individual nanostructures are imaged by time resolved scanning Kerr microscopy. The narrow linewidth of the magnetic excitations indicates a Gilbert damping constant of only α = 2.6 × 10 −4 rivalling the best values obtained for epitaxial YIG thin film material. The new fabrication process represents a leap forward in magnonics and magnon mechanics as it provides 3D YIG structures of unprecedented quality. At the same time it demonstrates a completely new route towards the fabrication of free standing crystalline nano structures which may be applicable also to other material systems.

We report on electrical resistivity, magnetic susceptibility, and magnetization on heat-capacity and optical experiments in single crystals of Sr 2 Ru 1Ϫx Ti x O 4 . Samples with xϭ0.1 and 0.2 reveal purely semiconducting resistivity behavior along c and the charge transport is close to localization within the ab plane. A strong anisotropy in the magnetic susceptibility appears at temperatures below 100 K. Moreover magnetic ordering in the c direction with a moment of order 0.01 B /f.u. occurs at low temperatures. On doping the lowtemperature linear term of the heat capacity becomes significantly reduced and probably is dominated by spin fluctuations. Finally, the optical conductivity reveals the anisotropic character of the dc resistance, with the in-plane conductance roughly following a Drude-type behavior and an insulating response along c.

Electron paramagnetic resonance (EPR) investigations of BaTiO +  0.04 BaO  +  x/2 FeO (0.007  ⩽  x  ⩽  0.05) ceramics and BaTiFeO single crystals were performed to study the incorporation of Fe ions in the hexagonal 6H-BaTiO lattice and their defect properties. The samples were characterized by x-ray diffraction and wavelength-dispersive x-ray electron probe microanalysis. EPR spectra were recorded both in X- and Q-bands at room temperature. Angle-dependent single crystal EPR investigations and simulations of the ceramic powder EPR spectra revealed three different centers, which can be attributed to Fe ions incorporated on crystallographically different Ti sites. Only one of them was already known before. Two spectra with axial symmetry belong to isolated Fe ions incorporated at Ti(1) sites (exclusively corner-sharing oxygen octahedra) and Ti(2) sites (face-sharing octahedra). The difference of their spectral parameters arises from the different trigonal distortions of the two types of octahedra. The third spectrum has orthorhombic symmetry and is caused by Fe centers associated with a nearest-neighbor charge-compensating oxygen vacancy. A model for the location of this associate is proposed.