J. Scola

Magnetic properties of the magnetophotonic crystal based on bismuth iron garnet

This article reports on the magnetism of continuous and patterned bismuth iron garnet (Bi3Fe5O12 or BIG) thin films for magnetophotonic crystal (MPC) applications. The exact knowledge of the magnetic properties is crucial for the design of fully functional MPC. BIG thin films were grown on several types of isostructural substrates by pulsed laser deposition. The growth conditions and bismuth transfer were optimized to obtain good quality magneto-optically active films compatible with nanostructuring process. MPC were successfully fabricated from BIG/GGG(001) films with low roughness and high Faraday rotation. Magnetic characteristics (magnetization, anisotropy, magnetic domains, magnetization reversal) of the continuous BIG films and MPC were extensively studied and compared to the results of the micromagnetic simulations performed for MPC with different anisotropy. The present study shows that the fabrication of the MPC structure lowers the magnetocrystalline and uniaxial in-plane anisotropies and induce...

Structural, optical, and magnetic properties of the ferromagnetic semiconductor hematite-ilmenite Fe2-xTixO3-δ thin films on SrTiO3(001) prepared by pulsed laser deposition

Structural, electrical, and magnetic properties of epitaxial thin films of Fe1.5Ti0.5O3−δ grown by pulsed laser deposition on SrTiO3(001) have been studied. For all the investigated range of preparation conditions, the thin films are single phase. The films prepared using oxygen pressure PO2 above 3×10−7 Torr presents a R(3¯)c symmetry structure. A single phase with the R(3¯) symmetry is obtained for the substrate temperature Ts=730 °C and PO2=2.6×10−7 Torr. This sample showed a ferrimagnetic behavior with Curie temperature Tc above room temperature, with a high magnetic moment of 0.6 μB/formula at 300 K. The film containing the disordered R(3¯)c phase is weakly ferromagnetic, with a spin glass-like signature. Optical properties seem to be governed more by the oxygen vacancies induced during the growth, than by the atomic ordering of titanium.

Microstructure and self-exchange coupling in a YFeO3 film

The microstructure of a thick film of YFeO3 grown on (100)-SrTiO3 has been investigated by transmission electron microscopy. The film is divided into two different growth regions with the bottom part characterized by strong contrast variations in the high resolution transmission electron microscopy images indicating the presence of high strain fields. The top part of the film between 50 nm and the film surface shows a preferential growth of (001) YFeO3 ∥ (001) SrTiO3 columns with relaxation into a strain free state. The mosaicity of the film and the grain boundaries determine the exchange coupling between columns and results in a strong perpendicular magnetic anisotropy.

Experimental study of the correlation length of critical-current fluctuations in the presence of surface disorder: Probing vortex long-range interactions

We report on critical currents and voltage noise measurements in niobium strips in the superconducting state, in the presence of a bulk vortex lattice

Metastable states of a flux-line lattice studied by transport and small-angle neutron scattering

(Bl{B}_{C2})

Voltage noise and surface current fluctuations in the superconducting surface sheath

and in the surface superconducting state

On voltage-current characteristics and critical current in Bi-2212

({B}_{c2}lBl{B}_{C3})

Narrow-band noise due to the moving vortex lattice in superconducting niobium

. For homogeneous surfaces, the correlation length of the current fluctuations can be associated with the electromagnetic skin depth of vortex superficial instabilities. The modification of the surface state by means of low energy irradiation induces a strong modification of the critical current and of the noise. The appearance of a corner frequency in the spectral domain can be linked with the low wave vectors of the artificial corrugation. Since this latter occurs only for

Longitudinal and transverse noise in a moving vortex lattice

Bl{B}_{C2}

Why pinning by surface irregularities can explain the peak effect in transport properties and neutron diffraction results in NbSe2 and Bi-2212 crystals?

, we propose that the long-range interactions allow the correlation length to extend up to values imposed by the surface topography.