Searching for a Quantum Critical Point in Rh doped ferromagnetic Ce2.15Pd1.95In0.9

Abstract

Low temperature magnetic and thermal ( C m ) properties of the ferromagnetic (FM) alloys Ce 2.15 (Pd 1− x Rh x ) 1.95 In 0.9 were investigated in order to explore the possibility for tuning towards a quantum critical point (QCP) by doping Pd with Rh. As expected, the magnetic transition decreases from T = 4.1K at x = 0 with increasing Rh concentration. However, the phase boundary splits into two transitions, the upper being antiferromagnetic (AF) whereas the lower FM. The AF phase boundary extrapolates to T N = 0 for x cr ≈ 0.65 whereas the first order FM transition vanishes at x ≈ 0.3. The quantum critical character of the T N → 0 point is inferred from the divergent T dependence of the tail of C m /T observed in the x = 0.5 and 0.55 alloys, and the tendency to saturation of the maximum of C m ( T N )/ T currently observed in exemplary Ce compounds when T N → 0. Beyond the critical concentration the unit cell volume deviates from the Vegard´s law in coincidence with a strong increase of the Kondo temperature.