Spin reorientation and magnetic anisotropy in Y 2Co 17− xCr x ( x = 1.17–3.0) compounds

Abstract

Spin reorientation transitions and magnetic anisotropy in Y 2Co 17− x Cr x ( x = 1.17–3.0) compounds have been investigated by means of X-ray diffraction and magnetization measurements. The powder X-ray diffraction patterns show that most samples crystallize as a single phase with the rhombohedral Th 2Zn 17-type structure. However, in the compound Y 2Co 14Cr 3 the Th 2Zn 17 phase coexist with the hexagonal Th 2Ni 17-type phase. The lattice parameters a and c hardly change and the unit cell volume V increases slightly with increasing Cr content. The X-ray diffraction patterns of the aligned powder of the samples have confirmed that at room temperature the compound with x = 1.17 has planar anisotropy, but the compounds with x = 1.76, 2.34 and 3.00 have uniaxial anisotropy. Spin reorientation phenomena occur in all of the compounds. With increasing Cr content, the Curie temperature, the spin reorientation temperature, the spontaneous magnetization, and the anisotropy constant K 2 of the Y 2Co 17− x Cr x ( x = 1.17–3.0) compounds decrease strongly while the anisotropy constant K 1 increases in the range of x from 1.17 to 2.34 and then decreases in the range of x from 2.34 to 3.00.