Phase evolution and magnetic properties of HoIn{sub 3−x}Co{sub x}
The phase evolution of HoIn{sub 3−x}Co{sub x} exhibits the phase transformations from the original HoIn{sub 3} with cubic structure to the intermediated HoCo{sub 2}In with orthorhombic structure and to the final HoCo{sub 3} with rhombohedral structure. The corresponding magnetic states are found to closely associate with the structural phase transformation of HoIn{sub 3−x}Co{sub x}.With increasing Co contents, HoIn{sub 3−x}Co{sub x} are paramagnetic in region of x < 0.6, mixture of paramagnetic and ferromagnetic in range of 0.6 < x < 1.8, and ferromagnetic in range of 3 > x > 2.4 at room temperature, respectively. The field dependence of magnetization curves follows an equation of M=M{sub s}(1−a/H )+χH, where M{sub s} and χ are corresponding to the saturation moment and susceptibility; a is a parameter related to the external field. The fitting results show that the susceptibility increases with increasing Co contents and M{sub s} depends upon the Co content as well. It implies that the evolution of magnetic phases in HoIn{sub 3−x}Co{sub x} might originate from the change of exchange interaction from the one between the isolated Co spins and the surrounding conduction electrons in Co-poor regime to the one between Co-Co pairs mediated by the conduction electrons in Co-rich regime.