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 M3CrO 8 (M = Li, Na, K, Rb, Ca) are found to exhibit a variety of interesting the rmodynamic and magnetic properties. These include: (a) simple molecular str uctures and single-ion ground states (3d(1)) 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 sp ecific heats throughout the liquid helium temperature range; and (d) possib ility of tuning the thermodynamic properties via dilution with compatible l attices such as M3NbO8, We envisage possible applications of these compound s as model systems for the theoretical studies of magnetic chains as well a s heat sinks and refrigerants in the mK-4 K range. (C) 1999 Elsevier Scienc e Ltd. All rights reserved.