Density functional study of the magnetic coupling in V(TCNE)2

A simple model structure of the room-temperature magnetic semiconductor V(TCNE)(2) is proposed on the basis of available experimental data. The structural, electronic, and magnetic properties are investigated using hybrid-exchange density functional theory within periodic boundary conditions. A spin-polarized ferrimagnetic ground state with a total spin of 1 mu(B) per formula unit is identified. The analysis of the corresponding electronic band structure and spin distribution reveals strong interactions between the V ions and the [TCNE](center dot-) radicals, identified as spin carrying units. Within a simple Ising Hamiltonian, a strong antiferromagnetic coupling between the metal and its nearest-neighbor ligands is predicted which is consistent with the observed high-temperature magnetic ordering. The computed results provide useful insight into the physical origin of the exceptional magnetic behavior of V(TCNE)(2).