Coexistence of magnetic order and valence fluctuations in the Kondo lattice system Ce${}_2$Rh${}_3$Sn${}_5$

Abstract

We report on the electronic band structure, structural, magnetic and thermal properties of Ce${}_2$Rh${}_3$Sn${}_5$. Ce $L_{\mathrm{III}}$-edge XAS spectra give direct evidence for an intermediate valence behaviour. Thermodynamic measurements reveal magnetic transitions at $T_{N1}\approx$ 2.9 K and $T_{N2}\approx$ 2.4 K. Electrical resistivity shows behaviour typical for Kondo lattices. The coexistence of magnetic order and valence fluctuations in a Kondo lattice system we attribute to a peculiar crystal structure in which Ce ions occupy two distinct lattice sites. Analysis of the structural features of Ce${}_2$Rh${}_3$Sn${}_5$, together with results of electronic band structure calculations and thermodynamic data indicate that Ce2 ions are in an intermediate valence state with the ground state electronic configuration close to 4$f^0$, whereas Ce1 ions are trivalent (4$f^1$) and contribute to the low temperature magnetic ordering. Thus, our joined experimental and theoretical investigations classify Ce${}_2$Rh${}_3$Sn${}_5$ as a multivalent charge-ordered system.

12 pages with 10 figures (main manuscript) and 2 pages with 2 figures (supplementary information)