Magnetic properties of HoCoMn compounds with the 2:17-type structure

The structural and magnetic properties of Ho2Co17-xMnx (x=0-4) compounds have been investigated by means of X-ray diffraction (XRD) and magnetic measurements. Powder XRD patterns show that the compounds with x=1, 3, 4 are single phase with rhombohedral Th2Zn17-type structure while the compounds with x=0, 2 are a mixture of rhombohedral Th2Zn17-type phase and a trace of the hexagonal Th2Ni17-type phase. The substitution of Mn for Co leads to a linear increase in lattice constants a, c and unit cell volume v. The Curie temperature TC decreases linearly with increasing Mn substitution. The saturation moment firstly increases with increasing Mn substitution for x≤2, and then decreases. XRD measurement on magnetically aligned samples demonstrates that x=1 exhibits an easy-cone type of anisotropy at room temperature, x=2-4 exhibit an easy-axis type of anisotropy at room temperature. The spin-reorientation transitions are found in the M-T curves for all samples. The magnetic phase diagram is given. The magnetocrystalline anisotropy constants K1 and K2 are deduced from fitting the reversible recoil curve in the hard direction by a modified Sucksmith-Thompson plot. K1 increases with increasing Mn content and K2 is comparable to K1 in amplitude. The magnetocrystalline anisotropy field μ0HA is found first to increase and then decrease with increasing Mn concentration, attaining a maximum value of 3.7 T at x=3