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

TL;DR

This study investigates Ce$_2$Rh$_3$Sn$_5$, revealing coexistence of magnetic order and valence fluctuations due to its unique crystal structure, with distinct Ce sites exhibiting different valence states, combining experimental and theoretical insights.

Contribution

It provides the first detailed analysis of the coexistence of magnetic order and valence fluctuations in Ce$_2$Rh$_3$Sn$_5$, highlighting the role of its crystal structure and multivalent charge ordering.

Findings

Ce$_2$Rh$_3$Sn$_5$ exhibits magnetic transitions at ~2.9 K and ~2.4 K.

Ce ions occupy two distinct lattice sites with different valence states.

The compound is classified as a multivalent charge-ordered system.

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 $T_{\mathrm{N1}}\approx$ 2.9 K and $T_{\mathrm{N2}}\approx$ 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.