The suppression of hidden order and the onset of ferromagnetism in URu2Si2 via Re substitution

Substitution of Re for Ru in the heavy fermion compound URu2Si2 suppresses the hidden order transition and gives rise to ferromagnetism at higher concentrations. The hidden order transition of URu2-xRexSi2, tracked via specific heat and electrical resistivity measurements, decreases in temperature and broadens, and is no longer observed for x > 0.1. A critical scaling analysis of the bulk magnetization indicates that the ferromagnetic ordering temperature and ordered moment are suppressed continuously towards zero at a critical concentration of x approximate to 0.15, and this is accompanied by the additional suppression of the critical exponents gamma and delta - 1 towards zero. This unusual trend appears to reflect the underlying interplay between Kondo and ferromagnetic interactions, and perhaps the proximity of the hidden order phase.