Constrained DFT+U approach for understanding the magnetic behaviour of ACr2O4 (A = Zn, Mg, Cd and Hg) compounds
文摘
Inconsistent behaviour of nearest neighbour exchange coupling constant (J) predicted by Yaresko is studied in chromium spinels. Unconstrained calculations give the inconsistent sign of J and variation of its magnitude with increasing U for CdCr2O4 and HgCr2O4 for U>3 eVU>3 eV and U=2–6 eVU=2–6 eV, respectively. The sign of J and variation of its magnitude with increasing U observed in constrained calculations are consistent with experimental data and equation, J ∝t2U, respectively. The present study shows the importance of constrained calculations in understanding the magnetic behaviour of these spinels.