Understanding the heavy fermion behavior in CeInPt₄

Abstract

The cubic compound CeInPt₄ exhibits heavy fermion behavior with a high extrapolated value of the electronic specific heat, γ=2.5 J/mole K² as T→0 K. The specific heat does not exhibit any sign of long range magnetic ordering down to 100 mK. In order to understand the origin of the high value of γ and the nature of the 4f electrons of this compound, we have carried out neutron diffraction, low-field magnetic susceptibility, muon spin relaxation, and inelastic neutron scattering measurements on CeInPt₄. Our susceptibility results show that for temperatures between 20 and 1.5K, a power law behavior is exhibited, Χ(T)~T^-β with β=0.5. Below 1.5K, the susceptibility is almost temperature independent, again without any sign of magnetic ordering down to the lowest available temperature (300 mK). The muon spin relaxation measurements reveal that below 1K, the electronic relaxation rate strongly increases without any loss of muon initial asymmetry, indicating the presence of low energy spin fluctuations as an explanation for the high value of γ in CeInPt₄. Heat capacity data reveal a log(C/T)∝log(T) behavior, indicating that CeInPt₄ may exhibit non-Fermi-liquid behavior close to a T→0 K quantum critical point. Our inelastic neutron scattering results reveal a broad crystal field excitation centered at 25 meV, indicating the presence of strong hybridization between the 4f and the conduction electrons, which is consistent with the observed high value of the paramagnetic Curie temperature (θ_p=-255K).