Magnetic properties of Tb0.28Dy0.57Ho0.15Fe2-xMnx(x=0,0.05,0.1,0.15,0.2)

The pseudobinary Laves phase (RRFe2)-R-1-Fe-2 magnetostrictive compounds have one degree of freedom by which the largest anisotropy constant K-1 is minimized to obtain the best performing material. However, by including a third rare earth element, additional degree of freedom is obtained, which allows a better way to choose a material for application. In the present study, Ho has been chosen as it exhibits positive magnetostriction, similar to Tb and Dy. Substitution of Mn for Fe leads to the realization of improved magnetostriction values and reduction in the anisotropy. In the present paper magnetic properties of Tb0.28Dy0.57Ho0.15Fe2-xMnx(x=0,0.05,0.1,0.15,0.2) are presented. The compounds have formed in single phase with cubic Laves phase structure. The lattice parameter is found to increase from 7.327 to 7.347 A with increasing the Mn concentration to 0.2. The Fe/Mn-Fe/Mn distance is less than 2.66 A, the critical distance below which the Fe and Mn moments could be antiferromagnetically ordered, leading to a decrease in the Curie temperature from 592 to 537 K. At 80 K, saturation magnetization is found to increase from 120 emu/g (x=0) to 125 emu/g (x=0.1) and then to decrease to 105 emu/g (x=0.2). The magnetostriction increases from 1000x10(-6) (x=0) to 1050x10(-6) (x=0.1) with Mn and decreases to 775x10(-6) with further increment of Mn (x=0.2). Spontaneous magnetostriction is found by the splitting of the (440) peak.