First Principles Calculation of the Electronic Structure of V(TCNE)₂

Vanadium tetracyanoethylene, V(TCNE)₂, is a room temperature ferrimagnetic semiconductor with a T_c ~ 600 K, which has very low loss ferromagnetic resonance and spin-wave propagation. Previous first principles calculations of the electronic structure have indicated an indirect band gap at 0.8 eV, substantially larger than the 0.5 eV from experimental inference from the conductivity activation energy. [1] The study of Ref. 1 used a local-orbital calculation with B3LYP hybrid functional. Here we explore the electronic structure using a plane-wave code VASP and XC functional Heyd-Scuseria-Ernzerhof (HSE06). We confirm that the structure of VTCNE has a triclinic unit cell with each V atom surrounded by 6 organic ligands, as found in Ref. 1. However, in contrast to the previous study we find a direct band gap of 0.4 eV, instead of an indirect band gap, located at a different k-point. This band gap better agrees with the experiment. We also studied magnetic anisotropy, the optical properties, magnetic dynamics, and magnetoelastic properties.

[1] G. C. De Fusco, L. Pisani, B. Montanari, and N. M. Harrison, Phys. Rev. B 79, 085201 (2009).