ﻻ يوجد ملخص باللغة العربية
Pure ultrafine ZnFe2O4 particles have been obtained from mechanosynthesis of the ZnO and Fe2O3 oxides. The average grain diameter was estimated from x-ray diffraction to be <d> = 36(6) nm. Refinement of neutron diffraction (ND) data showed that the resulting cubic spinel structure is oxygen-deficient, with ~7% of Fe3+ ions occupying the tetrahedral A sites. Magnetization curves taken at 4.2 K showed absence of saturation up to fields H = 9 Tesla, associated to a spin-canted produced by the milling process. Field-cooled (FC) and zero-field-cooled (ZFC) curves showed irreversible behavior extending well above room temperature, which is associated to spin disorder. Annealing samples at 300 {deg}C yields an average grain size <d> = 50(6) nm, and ~16% of Fe3+ ions at A sites. Partial oxygen recovery is also deduced from neutron data refinement in annealed samples. Concurrently, decrease of magnetic irreversibility is noticed, assigned to partial recovery of the collinear spin structure. Complex Mossbauer spectra were observed at room temperature and 80 K, with broad hyperfine field distributions spanning from ~10 T to ~40 T. At T = 4.2 K, hyperfine field distributions indicate high disorder in Fe local environments. The above data suggest the existence of Fe-rich clusters, yielding strong superexchange interactions between Fe ions at A and B sites of the spinel structure.
We present a Density Functional Theory (DFT) based study of the structural and magnetic properties of the (001) surface of the semiconducting oxide ZnFe2O4 (spinel structure). The calculations were performed using the DFT based ab initio plane wave a
Dynamic recrystallization (DRX) is often observed in conjunction with adiabatic shear banding (ASB) in polycrystalline materials. The recrystallized nanograins in the shear band have few dislocations compared to the material outside of the shear band
Two-dimensional electron gas (2DEG) confined in quantum wells at insulating oxide interfaces have attracted much attention as their electronic properties display a rich physics with various electronics orders such as superconductivity and magnetism.
We have studied the effect of irreversibility induced by repeated thermal cycles on the electric transport and magnetization of polycrystalline samples of La0.5Ca0.5MnO3 and La0.325Pr0.3Ca0.375MnO3. An increase of the resistivity and a decrease of th
The ultrafine entanglement witness, introduced in [F. Shahandeh, M. Ringbauer, J.C. Loredo, and T.C. Ralph, Phys. Rev. Lett. textbf{118}, 110502 (2017)], can seamlessly and easily improve any standard entanglement witness. In this paper, by combining