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arXiv · 2008.12241

Nonmagnetic ground state, Crystal field effects and Heavy-fermion behaviour in the Remeika Phase: Pr$_3$Ir$_4$Ge$_{13}$

K. Ramesh Kumar·Michael O. Ogunbunmi·Harikrishnan S. Nair·Andre M. Strydom
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Abstract

We report the magnetic, electronic and transport properties of the quasi-skutterudite compound Pr$_3$Ir$_4$Ge$_{13}$ by means of magnetic susceptibility $\chi(T)$, electrical resistivity $\rho(T)$, specific heat $C_p(T)$, thermal conductivity $\kappa(T)$, thermoelectric power $S(T)$ and Hall coefficient $R_\mathrm{H}(T)$ measurements. Pr$_3$Ir$_4$Ge$_{13}$ does not show any phase transition down to 1.9 K. Magnetic, and specific measurements show that the system possesses a crystal electric field singlet ground state that is separated from the first excited state by about 37 K. $\rho(T)$ shows a negative temperature coefficient of resistance for the whole temperature range studied and which can be explained in terms of Mott's impurity band conduction mechanism. $R_\mathrm{H}(T)$ measurements show that Pr$_3$Ir$_4$Ge$_{13}$ is a low-carrier density semimetal and its transport properties indicate a metallic-non metallic cross over behaviour. Large Seebeck values were observed for the entire temperature range of investigation, and the analysis of temperature variation of $S$ and $S/T$ showed no sign of strong correlation between the Pr 4$f^2$ and conduction electron states near Fermi level. A large Sommerfeld coefficient, $\gamma = 150$~mJ/(mol K$^2$) indicates the formation of a moderate heavy-fermion state emerging from the dynamical crystal field fluctuations.

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K. Ramesh Kumar, Michael O. Ogunbunmi, Harikrishnan S. Nair, Andre M. Strydom. 2020-08-27. Nonmagnetic ground state, Crystal field effects and Heavy-fermion behaviour in the Remeika Phase: Pr$_3$Ir$_4$Ge$_{13}$. https://arxiv.org/abs/2008.12241

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