We report that small amounts of metal atom nonstoichiometry are possible in the ZnCr2O4 and MgCr2O4 spinels. The nonstoichiometry, though less than 2%, significantly impacts TN and the nature of the magnetic correlations above TN. The Zn 1+xCr2-xO4 spinel is particularly sensitive. While stoichiometric ZnCr2O4 displays antiferromagnetic short-range correlations in the susceptibility above TN, ferromagnetic correlations are observed in nonstoichiometric, hole-doped Zn 1+xCr2-xO4. The Mg1+xCr 2-xO4 spinels are less profoundly affected by non-stoichiometry, though significant changes are also observed. We contrast the magnetic properties of Zn1+xCr2-xO4 and Mg1+xCr2-xO4 (x = 0, 0.02, 0.04) with those of materials with the equivalent amounts of isovalent nonmagnetic Ga3+ substituted on the Cr3+ site to separate the effects of static site disorder and hole doping.
|Physical Review B - Condensed Matter and Materials Physics
|Published - Feb 11 2011
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics