Spin glass transitions in the absence of chemical disorder for the pyrochlores A2Sb2O7 (A=Mn, Co, Ni)

The pyrochlores in the series A2Sb2O7 have been synthesized and characterized as exhibiting spin glass transitions at TSG=41, 4.5, and 2.6K (for A=Mn2+ S=52, Co2+ S=32 and Ni2+ S=1, respectively) despite the lack of chemical disorder. Since the Curie–Weiss temperature remains essentially constant for all members in the series (θ∼−40K), the frustration index for these materials increases significantly as the moment size is reduced from …