Spin reorientation and magnetic anisotropy in Y2Co17−xCrx (x = 1.17-3.0) compounds

Spin reorientation transitions and magnetic anisotropy in Y2Co17−xCrx (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 Th2Zn17-type structure. However, in the compound Y2Co14Cr3 the Th2Zn17 phase coexist with the hexagonal Th2Ni17-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 K2 of the Y2Co17−xCrx (x = 1.17-3.0) compounds decrease strongly while the anisotropy constant K1 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.