Paramagnons in heavy-electron systems

Abstract

Paramagnons in heavy-electron systems are theoretically examined. First, local spin fluctuations are fully included in the best single-site approximation. A local Kondo temperature is uniquely defined to show a characteristic energy scale of local spin fluctuations. Secondly, paramagnons are included perturbatively. Such a theory is applied to analyze the specific-heat data of heavy-electron compounds such as ${\mathrm{UAl}}_{2}$, ${\mathrm{UPt}}_{3}$, and ${\mathrm{CeSi}}_{1.85}$, where anomalous ${\mathit{T}}^{3}$lnT terms are observed at low temperatures T10 K. It is argued that not only paramagnons but also local spin fluctuations are responsible for the low-temperature specific heat and that paramagnons are responsible for the anomalous ${\mathit{T}}^{3}$lnT terms.