Anisotropy and FOMP in Tb₃ (Fe₂₈₋ₓCoₓ) V₁.₀ (x=0, 3 and 6) compounds

Abstract

Anisotropy and FOMP in Tb3 (Fe28−xCox) V1.0 (x=0, 3 and 6) compounds

A. Gholizadeha, Corresponding Author Contact Information, E-mail The Corresponding Author, N. Tajabora, M. Behdania, M. Kriegischb, F. Kubelc, M. Schönhartb, F. Pourariand, R. Grössingerb a Department of Physics, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran b Institute of Solid State Physics, Vienna University of Technology, Austria c Institute of Chemical Technologies and Analytics, Vienna University of Technology, Austria d Department of Material Science & Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA

Received 23 May 2011; Accepted 9 June 2011. Available online 20 June 2011. Abstract

In this work, the structural and magnetic properties of Tb3 (Fe28−xCox) V1.0 (x=0, 3, 6) compounds have been investigated. The structural characterization of compounds by X-ray powder diffraction is an evidence for a monoclinic Nd3(Fe, Ti)29-type structure (A2/m space group). The refined lattice parameters a and b (but not c) and the unit cell volume V, obtained from the XRD data by the Rietveld method, are found to decrease with increasing Co concentration. The unit cell parameters behavior has been attributed to the smaller Co atoms and a preferential substitution of Fe by Co. The anisotropy field (Ha) as well as critical field (Hcr) was measured using the singular point detection (SPD) technique from 5 to 300 K in a pulsed magnetic field of up to 30 T. At T=5 K, a FOMP of type 2 was observed for all samples and persists at all temperatures up to 300 K. For sample x=0, Hcr=10.6 and 2.0 T at 5 and 300 K, respectively, is equal to that reported earlier. The occurrence of canting angles between the magnetic sublattices during the magnetization process instead of high-order anisotropy contributions (at room temperature are usually negligible) has been considered to explain the survival of the FOMP at room temperature. The anisotropy and critical fields behave differently for samples with x=0, 3 compared with x=6. The observed behavior has been related to the fact that the Co substitution for Fe takes place with a preferential entrance in the inequivalent crystallographic sites of the 3:29 structure. The contribution of the Tb-sublattice in the Tb3(Fe, V)29 compound with uniaxial anisotropy has been scaled from the anisotropy field measured on a Y3(Fe, V)29 single crystal with easy plane anisotropy.