Quest for the Origin of Heavy Fermion Behavior ind-Electron Systems

Abstract

Spin fluctuation is presumed to be one of the key properties in understanding the microscopic origin of heavyfermion-like behavior in the class of transition-metal compounds, including LiV 2 O 4 , Y(Sc)Mn 2 , and YMn 2 Zn 20 . In this review, we demonstrate by our recent study of muon spin rotation/relaxation that the temperature (T ) dependence of the longitudinal spin relaxation rate (λ ≡ 1/T 1 ) in these compounds exhibits a common trend of leveling off to a constant value (λ ∼ const.) below a characteristic temperature, T * . This is in marked contrast to the behavior predicted for normal metals from the Korringa relation, λ ∝ T/ν, where the spin fluctuation rate (ν) in the Pauli paramagnetic state is given as a constant, ν ≃ 1/[hD(E F )] [with D(E F ) being the density of states at the Fermi energy]. Thus, the observed behavior of λ implies that the spin fluctuation rate becomes linearly dependent on temperature, ν ∝ T , suggesting that heavy quasiparticles develop in a manner satisfying D(E F ) ∝ (m * ) σ ∝ 1/T at lower temperatures (σ determined by the electronic dispersion). Considering that the theory of spin correlation for intersecting Hubbard chains as a model of pyrochlore lattice predicts ν ∝ T , our finding strongly indicates the crucial role of t 2g bands which preserve the one-dimensional character at low energies due to the geometrical frustration specific to the undistorted pyrochlore lattice.

Revealing correlation effect of Co 3d electrons in La3Co4Sn13 and Ce3Co4Sn13 by infrared spectroscopy study

“…The same effect also causes the moderate mass enhancement observed in the specific heat measurement. In fact, Kondo lattice formation and heavy fermion behavior have been observed in d-electron systems, for example in LiV 2 O 4 [46][47][48][49][50][51][52][53]. It was proposed that the mechanism for the heavy quasi-particle formation in LiV 2 O 4 is similar to that of f-electron systems, i.e.…”

Coupled spin-charge-phonon fluctuation in the all-in/all-out antiferromagnet Cd2Os2O7

“…3(a). Here, a convincing evidence for the spin fluctuation as the origin of λ * manifests in its dependence on the longitudinal magnetic field B, which is described by the following equation [17]:…”

Revealing correlation effect of Co 3d electrons in La$_3$Co$_4$Sn$_{13}$ and Ce$_3$Co$_4$Sn$_{13}$ by infrared spectroscopy study

“…The same effect also causes the moderate mass enhancement observed in the specific heat measurement. In fact, Kondo latttice formation or heavy fermion behavior have been observed in the d-electron systems, for example in LiV 2 O 4 [47][48][49][50][51][52][53][54]. It was proposed that the mechanism for the heavy quasi-particle formation in LiV 2 O 4 is similar to the f-electron systems, i.e., hybridization between the localized A 1g band and the itinerant E g band arising from the combination effect of crystal field splitting and d-d Coulomb interaction [49].…”