Competition between Band Filling and Steric Effect in Ordered Double Perovskites Sr_2-xLa_xMnMoO₆

【Abstract】 The ordered double perovskites, Sr 2-x La_xMnMoO₆, were prepared by sol-gel reaction. Structural, magnetic, and electrical properties were investigated for a series of ordered double perovskites Sr 2-x La_xMnMoO₆ （0≤x≤1）. The compounds have a monoclinic structure （space group P2₁/n） and the cell volume expands monotonically with La doping. The T_C and the magnetic moment rise and the cusp-like transition temperature below which the magnetic frustration occurs shifts to high temperature as x increases. With La doping, electrical resistivity of Sr 2-x La_xMnMoO₆ decreases only at low doping levels （x≤0.2）; while at high doping levels （0.8≤x≤1）, electrical resistivity tends to increase greatly. The results suggest that the competition between band filling effect and steric effect coexists in the whole doping range, and the formation of ferrimagnetic interactions is not simply at the expense of antiferromagnetic interactions.更多还原