Electronic Structure and Magnetic States of Crystalline and Fullerene-Like Forms of Nickel Dichloride NiCl[sub 2

Abstract

The electronic structure and magnetic properties of the crystalline and fullerene-like forms of nickel dichloride NiCl2 are investigated in the framework of the local spin density functional theory. It is demonstrated that the band gap can be reproduced in the energy band spectrum of the NiCl2 compound with inclusion of the magnetic ordering in the calculation of the band structure. The metamagnetic nature of the NiCl2 dichloride (i.e., the transition from an antiferromagnetic phase to a ferromagnetic phase in a weak magnetic field) is explained in terms of a small difference (0.025 eV/cell) between the total energies of the ferromagnetic and antiferromagnetic phases. Polyhedral three-shell nanoparticles of the NiCl2 compound exhibit magnetic properties (the magnetic moment of nickel lies in the range 2.0–2.3 μB). For isostructural nanoparticles of the FeCl2 dichloride, the magnetic moment of iron is larger and falls in the range 4.2–4.5 μB, whereas nanoparticles of the CdCl2 dichloride are found to be nonmagnetic. The results of analyzing the interatomic interactions indicate that the composition of fullerene-like nanoparticles of the dichlorides under investigation can deviate from the 1: 2 stoichiometric composition.