Magnetic properties of oxide glasses containing iron and rare-earth ions

Abstract

Measurements of fundamental magnetic properties including not only dc and ac susceptibilities but also magnetic aging effects have been performed for aluminoborate glasses with high concentrations of iron and rare-earth R 3+ ions (R = Sm, Gd, and Tb) in order to give an insight into the magnetic structures and interactions in amorphous oxides containing both 3d transition metal and 4f rare-earth ions, which manifest magnetic interactions that differ from each other. We demonstrate that the antiferromagnetic interactions between iron and rare-earth ions as well as those between iron ions play a significant role for their magnetic properties, while those between rare-earth ions are of little importance. Most of the rare-earth ions remain paramagnetic even below the spin-freezing temperatures under the strong molecular field caused by the spin-glass freezing of the iron ions, as in the case of rare-earth garnet ferrites.

Formation, characterization and magnetic properties of maghemite γ-Fe2O3 nanoparticles in borate glasses

“…percentage of MnO or CoO in the glass synthesis load. As it was shown in series of works (i.e., [9]), interesting results can be obtained when doping oxides glasses with Fe and rare earth (RE) simultaneously. That is why we used RE and some other large-ion-radius elements as co-dopants in order to maximize the magnetooptical activity of potassium-alumina-germanium-borate glasses.…”

Ferromagnetic amorphous oxides in the EuO-TiO2system studied by the Faraday effect in the visible region and the x-ray magnetic circular dichroism at the EuM4,5andKawamoto1, Fujita2, Akamatsu3 et al. 2013Phys. Rev. BSelf Cite7420View full textAdd to dashboardCite

“…In amorphous magnetic oxides, where the magnetic cations are randomly distributed in the three-dimensional disordered network, short-range antiferromagnetic superexchange interactions via the O 2p states, based on the Kramers-Anderson mechanism, are predominant as demonstrated by the fact that negative values of Weiss temperature have been reported for most of the oxide glasses. [1][2][3][4][5][6][7][8] The random distribution of the magnetic ions and the prevailing antiferromagnetic superexchange interaction among the magnetic ions inevitably cause geometrical frustrations in the ordering of the magnetic moments, leading to spin-glass transitions at low temperatures. [1][2][3][4][5][6][7][8] Consequently, oxide glasses containing a high concentration of magnetic ions are typical of insulating spin-glass systems where long-range interactions such as Ruderman-Kittel-Kasuya-Yoshida interactions are not at work.…”

Magnetic nanoparticles in borate glasses: Identification and sizing

“…In a recent paper [25] devoted to magnetic properties including dc and ac susceptibilities and magnetic aging effects in alumina-borate glasses doped with high concentrations of iron and RE ions (RE = Sm, Gd, and Tb), a possibility of iron ions forming magnetic clusters is suggested but the formation of magnetic nanoparticles is not considered. On the other hand, it has been shown [26,27] that potassiumalumina-germanium-borate glasses co-doped with relatively low concentrations (about 5 mass % in the total) of Fe 2 O 3 and RE 2 O 3 have a tendency towards the magnetic nanoparticle precipitation while remaining transparent in the visible and IR spectral range and demonstrating a large Faraday rotation.…”