Synthesis and magnetic properties of fergusonite-structured La(NbVMn)O₄

The authors have synthesized fergusonite-structured La(Nb_0·71V_0·04Mn_0·25)O₄ samples. The samples, consisting of La³⁺, Nb⁵⁺, V⁵⁺, Mn⁴⁺ and oxygen ions, demonstrated temperature-dependent magnetization that increased with lowering the temperature below ≈200 K, and almost saturated below ≈100 K. At 75 K, the field-dependent magnetization demonstrated sigmoidal curve and reached 3 μ_B/Mn at 1 T. Such a magnetic behavior can be ascribed to exchange interaction between Mn⁴⁺Nb₂O₁₁ nanoclusters. The Mn⁴⁺ substitution for the V⁵⁺ sites of the crystal resulted also in the occupied state above the valence band maximum.