Ion beam synthesis of Fe nanoparticles in MgO and yttria-stabilized zirconia

Abstract

To form embedded Fe nanoparticles, MgO(001) and YSZ(001) single crystals have been implanted at elevated temperatures with Fe ions at energies of 100keV and 110keV, respectively. The ion fluence was fixed at 6×1016cm−2. As a result, γ- and α-phase Fe nanoparticles were synthesized inside MgO and YSZ, respectively. A synthesis efficiency of 100% has been achieved for implantation at 1273K into YSZ. The ferromagnetic behavior of the α-Fe nanoparticles is reflected by a magnetic hyperfine field of 330kOe and a hysteretic magnetization reversal. Electron holography showed a fringing magnetic field around some, but not all of the particles.

Magnetic and optical properties of virgin arc furnace grown MgO crystals

“…Recently, MgO and other oxide hosts (TiO, ZnO, etc.) are studied with respect to embedded ferromagnetic nanoparticles, which can be used for ultrahigh density data storage devices [5][6][7][8]. Therefore the impurities content, even at very low level (in the ppm range) in as-grown MgO crystals may contribute to the final magneto-optical properties of the MgO crystals, especially optically active transition metals as Mn, Cr and V [9][10][11].…”

On the phenomena occurring at the interface between iron and iron–platinum thin films

“…By increasing the thickness of the soft layer, the coercive field of the bi-layers decreases and the magnetization tends to align parallel to the film plane, reaching [10] during the e-beam evaporation in zones which remained shielded by the substrate locking during the FePt sputtering the complete reorientation for a Fe layer 14 nm thick. However, no evidence was detected of a loss of the exchange coupling between the soft and hard phases.…”

Fe nanoparticles embedded in MgO crystals

“…6 Magnetic nanoparticles embedded into MgO, TiO 2 , ZnO, and other crystals fulfill this condition, being epitaxially related to the surrounding matrix. [7][8][9] In the temperature range from several kelvins to several hundred kelvins, two structural phases of cubic iron nanoparticles are usually observed: body-centered cubic ͑bcc͒ and facecentered cubic ͑fcc͒. For bulk crystals, the fcc iron ͑␥-Fe͒ phase appears as a result of phase transition at temperature above 1200 K. 10 Nowadays, the synthesis of ␥-Fe, stable below 1200 K, is possible only in the case of nanoparticles and ultrathin films.…”

“…In spite of numerous experimental reports, describing the phase and magnetic transitions of iron, the basics of these changes are still not well understood. In a recent study, 8 ␥-Fe nanoparticles embedded in MgO and YSZ ͑yittria stabilized zirconia͒ crystals, synthesized by ion implantation, have been observed at room temperature. Also, Haneda et al 11 observed extremely stable fcc iron nanoparticles with dimensions of about 8 nm at temperature of 1.8 K. However the explanations for the magnetic behavior of fcc iron are quite different.…”