Magnetic gap in Slater insulator α′-NaV₂O₅

Abstract

The electronic structure of room-temperature (RT) phase α -NaV 2 O 5 has been investigated by fully self-consistent first-principles calculations based on density functional theory (DFT). For the crystallographic unit cell, a nonmagnetic (NM) metallic solution is obtained by spin-restricted generalized gradient approximation (GGA) calculations, whereas a ferromagnetic (FM) insulating solution is successfully simulated within the spin-polarized GGA. An insulating antiferromagnetic (AFM) state with lower energy is obtained for the 1 × 2 × 1 crystallographic supercell. The magnetic S = 1/2 electrons are fully spin-polarized and delocalized on the V-O-V molecular orbitals (along the rung), where the net spin magnetic moments amount to 0.96 μ B on the V-O-V rungs of the ladder derived from Mulliken population analysis. The intra-rung vanadium d xy orbitals form the bonding-antibonding orbitals split by inter-orbital interactions. It is not the on-site Coulomb interaction, but the AFM spin exchange couplings that lead to the half-filled bonding orbitals splitting and forming a magnetic insulating gap. The present spin-polarized DFT calculations reveal that α -NaV 2 O 5 (RT) is a Slater insulator. The calculated electronic structure explains the controversial topics of the absorption peak in the optical spectra and the energy loss peak in the resonant inelastic x-ray scattering (RIXS).

First-principles study of phonons, optical properties, and Raman spectra inMgV2O5

“…For example, it needs to be clarified whether the experimentally determined space group reflects the symmetry of the stoichiometric unit cell or to which extent, e.g., defects could be responsible for structural distortions. In this context it should be noted that Ming et al 31 recently suggested that the actual structure of NaV 2 O 5 is a 1ϫ 2 ϫ 1 crystallographic supercell, where the antiferromagnetic spin exchange gives rise to the insulating gap. This result was obtained by spin-polarized GGA calculations, demonstrating that the main effect for the electronic properties around the Fermi level is not due to strong on-site Coulomb correlations.…”

Synthesis and characterizations of highly crystallized α′-NaV2O5 needles prepared by a hydrothermal process

“…1. The material has been widely investigated both experimentally and theoretically after the discovery of spin-Peierls behaviour [4][5][6]. Its spin magnetic susceptibility fits well to a Bonner-Fisher curve above 34 K and shows a one-dimensional antiferromagnetic chain along the 0 1 0 axis.…”

A Novel Process for the Synthesis of NaV2O5 Mesocrystals from Alkaline-Stripped Vanadium Solution via the Hydrothermal Hydrogen Reduction Method

“…In the NaV 2 O 5 structure, Na-ions are located in the interlayer space [5][6][7]. NaV 2 O 5 initially drew much attention for its spin-Peierls property [8][9][10][11][12][13][14][15]. In recent years, NaV 2 O 5 has been considered to have a potential application as the cathode material in lithium ion batteries or sodium ion batteries owing to its layered orthorhombic structure [16][17][18][19].…”