Unusual magnetic properties and thermal expansion in chromium pyrochlores Ln2CrTaO7, Ln = Y, Sm, Gdстатья
Информация о цитировании статьи получена из
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Дата последнего поиска статьи во внешних источниках: 24 сентября 2020 г.
Аннотация:New complex Cr-containing pyrochlores Ln2CrTaO7, Ln = Y, Sm, Gd, were synthesized. The Rietveld refinement of the Ln2CrTaO7 composition confirmed the pyrochlore type of the structure. The Cr3+ oxidation state is corroborated by XANES spectra. The detailed study of DC and AC magnetization of Ln2CrTaO7, Ln = Y, Sm, Gd, was carried out in the temperature range 2–300 K and magnetic field up to 5 T. FM phase transitions at 143, 192, and 163 K were observed in pyrochlores with Y, Sm, and Gd, respectively. It is shown that these transitions are due to canted antiferromagnetism or weak-ferromagnetism in the Ln2CrTaO7 pyrochlores. AFM interactions between Ln- and Cr-sublattices in Sm2CrTaO7 and Gd2CrTaO7 causes AFM transition at T = 42 K, after which magnetization continues increasing. Unusual magnetic properties were observed for Gd2CrTaO7 at low temperatures. Competitive FM and AFM interactions in Cr-and Gd-sublattice give rise to the occurrence of reentrant spin glass at T < 20 K. FM transition at 11 K is also detected. Spin glass state exists along with strong FM interactions. The effect of the magnetic properties on thermal expansion is also investigated for these compounds.