Phase evolution and magnetic properties of HoIn3−xCox

Abstract

The phase evolution of HoIn3−xCox exhibits the phase transformations from the original HoIn3 with cubic structure to the intermediated HoCo2In with orthorhombic structure and to the final HoCo3 with rhombohedral structure. The corresponding magnetic states are found to closely associate with the structural phase transformation of HoIn3−xCox.With increasing Co contents, HoIn3−xCox 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=Ms(1−aH)+χH, where Ms 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 Ms depends upon the Co content as well. It implies that the evolution of magnetic phases in HoIn3−xCox 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.