G-type antiferromagnetism of Mn ions in A-site-ordered perovskite LaMn3Rh4O12 and La0.8Ca0.2Mn3Rh4O12

Abstract A-site-ordered perovskites LaMn3Rh4O12 and La0.8Ca0.2Mn3Rh4O12 were prepared by using high-pressure and high temperature method. Structural and BVS analyses suggest that the valence states of Mn and Rh ions are both +3 in LaMn3Rh4O12. Partial Ca-doping introduced some Mn4+ ions, which are transferred to B site and leave some deficiencies at A′ site. Localized electrons of Mn and Rh ions induce a semiconducting behavior. Combined with the results of the first principles calculation, it is believed that the interaction between high spin Mn3+ ions induce a G-type antiferromagnetism, while low spin Rh3+ ions have no magnetic contribution. And also, there is no interaction between Mn and Rh ions. The results confirm that non-Jahn-Teller distorted Mn4+ ion cannot occupy A′ site in the A-site-ordered perovskite, even partly.