Collapse of the Kondo state and ferromagnetic quantum phase transition in YbFe 2Zn 20
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We present the electrical resistivity data under application of pressures up to ∼26 GPa and down to 50 mK on YbFe2Zn20. We find a pressure induced magnetic phase transition with an onset at pc=18.2±0.8 GPa. At ambient pressure, YbFe2Zn20 manifests a heavy fermion, nonmagnetic ground state and the Fermi liquid behavior at low temperatures. As pressure is increased, the power law exponent in resistivity, n, deviates significantly from Fermi liquid behavior and tends to saturate with n=1 near pc. A pronounced resistivity maximum Tmax, which scales with the Kondo temperature, is observed. Tmax decreases with increasing pressure and flattened out near pc indicating the suppression of Kondo exchange interaction. For p>pc,Tmax shows a sudden upward shift, most likely becoming associated with crystal electric field scattering. Application of magnetic field for p>pcbroadens the transition and shifts it toward the higher temperature, which is a typical behavior of a transition towards a ferromagnetic state, or a state with a significant ferromagnetic component. The magnetic transition appears to abruptly develop above pc, suggesting probable first-order (with changing pressure) nature of the transition; once stabilized, the ordering temperature does not depend on pressure up to ∼26 GPa. Taken as a whole, these data suggest that YbFe2Zn20 has a quantum phase transition at pc=18.2 GPa associated with the avoided quantum criticality in metallic ferromagnets.