Metallic conductivity and a Ca substitution study of NaRh2O4 comprising a double chain system

TL;DR

This study investigates the metallic NaRh2O4 and its solid solution with CaRh2O4, revealing magnetic contributions to specific heat at low temperatures without evidence of a magnetic phase transition.

Contribution

It provides new insights into the magnetic origin of low-temperature specific heat anomalies in NaRh2O4-CaRh2O4 solid solutions.

Findings

Low-temperature specific heat has a magnetic origin.

Magnetic entropy is about 1% of a simple splitting doublet.

No magnetic phase transition observed.

Abstract

The metallic compound NaRh2O4 forms a full range solid solution to the insulating phase CaRh2O4. At a Na concentration of 0.25 moles per formula unit, we found an unexpected contribution to the specific heat at low temperature [K. Yamaura et al. Chem. Mater. 17 (2005) 359]. To address this issue, specific heat and ac and dc magnetic susceptibilities were additionally measured under a variety of conditions for the Na0.25 sample. A new set of data clearly indicate the additional specific heat is magnetic in origin; however, the magnetic entropy is fairly small (~1 % of Schottky term for a simple splitting doublet), and there is no other evidence to suggest that a magnetic phase transition is responsible for the anomalous specific heat.