Alkali-metal peroxychromates: Cr(V)-based antiferromagnets with low-dimensional spin exchange and high specific heats

The Cr(V) based alkali-metal peroxychromates with the general formula M3CrO8 (M=Li, Na, K, Rb, Cs) are found to exhibit a variety of interesting thermodynamic and magnetic properties. These include: (a) simple molecular structures and single-ion ground states (3d1) which depend sensitively on a specific cation as well as combinations of the cations in a solid solution (mixed crystals); (b) low dimensionality of the magnetic interactions that lead to a variety of phase transitions depending on the cation; (c) high specific heats throughout the liquid helium temperature range; and (d) possibility of tuning the thermodynamic properties via dilution with compatible lattices such as M3NbO8. We envisage possible applications of these compounds as model systems for the theoretical studies of magnetic chains as well as heat sinks and refrigerants in the mK–4 K range.