
Accession Number : AD0612847
Title : ASPHERICAL SPIN DENSITY IN SSTATE CATIONS,
Corporate Author : MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
Personal Author(s) : Kaplan,T. A.
Report Date : 18 JUN 1964
Pagination or Media Count : 5
Abstract : A calculation of the firstorder effect of spinorbit coupling on a (3d)(5) unperturbed Sstate ion in a cubic crystal field has led to a new contribution sigma1 (r) to the ionic spin density. The integral over space of sigma1 (r) is zero and sigma1 (r) is perpendicular to the unperturbed spin density sigma0 (r); while sigma0 (r) is spherically symmetric about the nucleus, sigma1 (r) is highly aspherical. In alphaFe2O3 at room temperature, the spin density consists of the large ''antiferromagnetic'' component sigma0, plus the new term sigma1, plus the weak ferromagnetic or Dzialoshinsky term sigmaD, which is spherical. In neutron scattering, it is found that sigma1 contributes to the same ''ferromagnetic'' Bragg peaks as does sigmaD, and in the same order of magnitude. Hence the new term is probably important for understanding the surprising, highly aspherical ferromagnetic spindensity distribution recently observed in alphaFe2O3 by Pickart, Nathans, and Halperin. In general, sigma1 (r) will be nonzero under much less restrictive symmetry requirements than those needed for the nonvanishing of sigmaD. In the course of discussion, it is pointed out that the DzialoshinskyMoriya theory of the weak ferromagnetism in alphaFe2O3, for example, implies that the application of a spatially uniform magnetic field should influence the distribution of domains of antiferromagnetic spin components. This effect was observed by Pickart et al. (Author)
Descriptors : (*CRYSTAL LATTICES, NUCLEAR SPINS), (*NUCLEAR SPINS, DENSITY), (*ANTIFERROMAGNETISM, NUCLEAR SPINS), (*IRON COMPOUNDS, OXIDES), IONS, ATOMIC ORBITALS, ATOMIC ENERGY LEVELS, FERROMAGNETISM, NEUTRON SCATTERING, QUANTUM STATISTICS
Distribution Statement : APPROVED FOR PUBLIC RELEASE