Magnetic susceptibility of pyrochlores R2Ti2O7: R = Gd, Dy, Tb

Abstract We present the study of magnetic susceptibility of pyrochlores Gd2Ti2O7, Dy2Ti2O7 and Tb2Ti2O7 which belong to frustrated magnets. The temperature dependence of the susceptibility χ ( T ) of powder samples was measured in the temperature range from 4.2 to 300 K and analyzed in the framework of mean field approximation taking into account both crystal field effects and anisotropy of the exchange interaction. We developed a simple approach allowing us to estimate interaction energies of magnetic ions from χ ( T ) dependences and data on wave functions of the crystal-field states of the ions using a minimum number of fitting parameters. We revealed a strong anisotropy of the exchange interaction in the paramagnetic state of Gd2Ti2O7 and obtained nearest-neighbor effective bond energies of the magnetic ions in Tb2Ti2O7 and Dy2Ti2O7 which are in good agreement with the temperatures of formation of the spin-ice state in these compounds.