Papers by Keyword: Magnetotransport Properties

Abstract: We report on structural and transport properties of Ni-Mn-In thin films. The results obtained have indicated that transport properties of the thin films strongly depend on the structural ordering of the films. Specifically, annealing converts the semiconducting-like character of the resistivity into that typical for metals. This is due to annealing-induced crystallization of as-deposited films which are in partially amorphous state. In both the as-deposited and the annealed thin films the field dependence of the resistivity is negative, which is typical for thin films of Heusler alloys and can be ascribed to the suppression of the spin disorder scattering.

Abstract: A-site ordered PrBaMn2O6 manganites were obtained by a two-step synthesis process. The chemical composition, crystal structure, magnetic and magnetotransport properties have been investigated with regard to the degree of ordering of the Pr3+ and Ba2+ cations. A-site disordered Pr0.50Ba0.50MnO3 has a cubic perovskite-like unit cell (SG = Pm3m , Z = 1), while the A-site ordered PrBaMn2O6 has a tetragonal unit cell (SG = P4/mmm, Z = 2). The A-site ordered state in PrBaMn2O6 remains stable on heating to 1300 0C in an oxidizing medium (P[O2] = 1 bar). The cation ordering leads to a significant increase in the critical temperatures of phase transitions. Asite ordered PrBaMn2O6 is a metallic ferromagnet with the TC ~ 320 K, whereas TC of a fully disordered sample is ∼ 140 K. The samples with intermediate degrees of ordering contain two magnetic phases. Slightly below TC, all samples exhibit a metal–insulator transition and a peak of the magnetoresistance, amounting to approximately 10 % and 65 % in a magnetic field of 9 kOe for the fully ordered PrBaMn2O6 and disordered Pr0.50Ba0.50MnO3, respectively. The results are interpreted in terms of the degree of ordering of the Pr3+ and Ba2+ cations.

Abstract: Multistep current annealing (CA) treatments were performed on amorphous FINEMETtype Fe-Cu-V-Si-B, as well as on a novel Fe-Al-Ga-P-C-B alloy with a large supercooled liquid region, in order to optimize their magnetotransport properties. On-line and post-annealing electrical resistivity measurements, DSC, XRD and Mössbauer spectroscopy were used for characterization of structural changes evolved during CA treatments. Results on magnetoresistance (MR) and magnetoimpedance (MI) effects after CA in ribbon samples with relaxed amorphous as well as precipitated nanocrystalline structure are presented. Significant improvement in MI-response after CA up to
Z/Z ≈ 50% was recorded at frequencies 2-3 MHz. The highest MI-element sensitivity was found for low magnetic field intensity where values of about 6 %/kA/m for samples of Fe-Al- Ga-P-C-B alloy were attained.