Magnetic and thermal investigations of the rubidium rare earth double tungstates RbRE(WO₄)₂ (RE= Dy, Nd, Sm) have been performed and compared with some potassium rare earth double tungstates.. Rubidium rare earth double tungstate single crystals have been grown by the top-seeded solution growth method (TSSG). They crystallize in the monoclinic crystal structure, with the C2/c space group. Using the X-ray diffraction measurements the unit cell parameters have been determined.

The magnetic properties as a function of both temperature and magnetic field intensity have been studied. The magnetization has been measured in the temperature region from 4.2 K to 100 K and in magnetic field up to 1.45 T. A strong anisotropy of magnetic properties was found. The data on temperature and field dependencies of magnetization was used to determinate the exchange interaction parameters. Results of study of magnetic properties of the rubidium rare earth double tungstates have been compared with result obtained for potassium rare earth double tungstates.

The specific heat measurements in these single crystals are also presented. The specific heat C(T) of the RbDy(WO₄)₂, RbNd(WO₄)₂ and RbSm(WO₄)₂ crystals have been measured over a temperature range of 1.6 –300 K in magnetic field up to 10 T.

These crystals are established to be new perspective materials for an adiabatic demagnetization.

This work was supported by EU project DT-CRYS, NMP3-CT-2003-505580, by Polish State Committee on Science (KBN) (decision of project No. 72/E-67/SPB/6. PR/DIE 430/2004-2006).