2020, Kuznetsov, A. V., Churkin, O. A., Ivanov, A. A., Popov, V. V., Alekseev, P. A., Menushenkov, A. P., Кузнецов, Алексей Владимирович, Чуркин, Олег Алексеевич, Иванов, Андрей Анатольевич, Попов, Виктор Владимирович, Алексеев, Павел Александрович, Менушенков, Алексей Павлович

© 2019We 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.

2020, Kuznetsov, A. V., Churkin, O. A., Popov, V. V., Shchetinin, I. V., Ivanov, A. A., Yaroslavtsev, A. A., Gaynanov, B. R., Yastrebtsev, A. A., Chernysheva, O. V., Alekseev, P. A., Menushenkov, A. P., Кузнецов, Алексей Владимирович, Чуркин, Олег Алексеевич, Попов, Виктор Владимирович, Иванов, Андрей Анатольевич, Гайнанов, Булат Радикович, Ястребцев, Алексей Алексеевич, Чернышева, Ольга Викторовна, Алексеев, Павел Александрович, Менушенков, Алексей Павлович

We present the study of frustrated magnets R2M2O7, where R = Gd, Dy, Tb and M = Ti, Zr. Magnetic susceptibility chi and low-temperature magnetization of perfectly ordered pyrochlores R2Ti2O7, partially disordered fluorites R2Zr2O7, and their completely disordered amorphous phases were measured and analyzed. We have found that structural disorder weakens the exchange interaction of the rare-earth ions. Magnetic moments of dysprosium and terbium, obtained from nearly saturated magnetization, are slightly affected by the disorder while the gadolinium moment is completely independent of it. The local structure of the compounds, including oxygen environment of the rare-earth ions, is discussed in terms of the influence of the crystal electric field on the magnetic properties of R2M2O7.