Evolution of Critical Scaling Behavior near a Ferromagnetic Quantum Phase Transition

Magnetic critical scaling in URu2-xRexSi2 single crystals continuously evolves as the ferromagnetic critical temperature is tuned towards zero via chemical substitution. As the quantum phase transition is approached, the critical exponents gamma and (delta - 1) decrease to zero in tandem with the critical temperature and ordered moment, while the exponent beta remains constant. This novel trend distinguishes URu2-xRexSi2 from stoichiometric quantum critical ferromagnets and appears to reflect an underlying competition between Kondo and ferromagnetic interactions.