Massimo Solzi

Abstract We review the composition dependence of the structural and magnetic properties of the Co-doped Ni–Mn–Ga Ferromagnetic Shape Memory Alloy around the Mn-rich composition Ni50Mn30Ga20. The presence of Co affects the critical temperatures and ...

La0. 7Sr0. 3MnO3 polycrystalline manganite thin films were grown on silicon (Si) substrates covered by SiOx amorphous native oxide. Curie temperatures of about 325K were achieved for 70-nm-thick films. Strong room temperature XMCD signal was detected indicating high ...

The effect of the AlOx barrier thickness on magnetic and morphological properties of Ta/Co/(AlOx)/Alq3/Si hybrid structures was systematically studied by means of atomic force microscopy, superconducting quantum interference device magnetometry, and nuclear magnetic resonance (NMR). All used techniques pointed out that the barrier thickness of 2 nm is required to obtain a magnetically good cobalt layer on top of Alq3.

ABSTRACT Nanoparticles of MnFe2O4 were synthesized via sol-gel method, with calcination processes at 400 degrees C and 500 degrees C in air. The effects of the different calcinations in the formation of the crystal structure and magnetic and optical properties were studied with X-ray diffraction (XRD), electron microscopy, SQUID magnetometer, and optical absorption. The XRD studies reveal the formation of a phase corresponding to cubic spinel structure in both samples and the presence of a second phase identified as Fe2O3, in the case of the sample with higher temperature treatment. The TEM images of the first sample show small nonuniform nanoparticles with a mean size of 7.8 nm, with a strong tendency to form agglomerates. Magnetization studies as a function of temperature were carried following field-cooled (FC)-Zero-field-cooled (ZFC) routines, where the ZFC curves exhibit blocking temperatures close to 250 K in both cases, and the behavior of the samples below this temperature suggests strong interaction between the particles. In the magnetization as a function of magnetic field studies, the curves display a tendency to saturate at low temperatures and the system shows superparamagnetic behavior above the blocking temperature. Saturation magnetization values ( at low temperatures) are low compared to the expected ones, according to the Neel model of collinear spins, this can be attributed to canting effects or the presence of a second antiferromagnetic phase, specifically in the sample treated at 500 degrees C. No significant differences were observed in the magnetic behavior of the samples. Semiconducting characteristics of the ferrites were confirmed by optical absorption measurements, obtaining an energy gap value close to 2.23 eV at room temperature.

Ultrathin ferromagnetic films of La0.7Sr0.3MnO3 were deposited by electron-beam ablation on standard SrTiO3(100) and NdGaO3(110) substrates. Even 4nm films are metallic and develop spontaneous magnetization at room temperature: similar hysteresis cycles were measured by magneto optical Kerr effect (MOKE) in the longitudinal configuaration and by SQUID magnetometry. To the best of our knowledge the 4nm thickness corresponds so far to