Anisotropy in magnetic properties and electronic structure of single-crystal LiFePO4

TitleAnisotropy in magnetic properties and electronic structure of single-crystal LiFePO4
Publication TypeJournal Article
Year of Publication2008
AuthorsLiang G, Park K, Li JY, Benson RE, Vaknin D, Markert JT, Croft MC
Journal TitlePhysical Review B
Volume77
Pages064414
Date PublishedFeb
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberISI:000253764100051
KeywordsCATHODE MATERIALS, diffraction, ION BATTERIES, iron, performance, RECHARGEABLE LITHIUM BATTERIES, spectroscopy, susceptibility, temperature, X-RAY-ABSORPTION
Abstract

We report the experimental and theoretical results on the anisotropies in the magnetic properties and x-ray absorption spectra of single-crystal LiFePO4. A mean-field theory is developed to explain the observed strong anisotropies in Lande g-factor, paramagnetic Curie temperature, and effective moment for LiFePO4 single crystals. The values of the in-plane nearest- and next-nearest-neighbor spin exchange (J(1) and J(2)), interplane spin exchange (J(perpendicular to)), and single-ion anisotropy (D), obtained recently from neutron scattering measurements, are used for calculating the Curie temperatures with the formulas derived from the mean-field Hamiltonian. It is found that the calculated Curie temperatures match well with that obtained by fitting the magnetic susceptibility curves to the modified Curie-Weiss law. For the polarized Fe K-edge x-ray absorption spectra of single-crystal LiFePO4, a different feature assignment for the 1s -> 4p transition features is proposed and the anisotropy in the intensities of the 1s -> 3d transition features is explained adequately by a one-electron theory calculation of the electric quadrupole transition terms in the absorption coefficient.

DOI10.1103/PhysRevB.77.064414
Alternate JournalPhys. Rev. B