Anders Hjelm

ORBITAL PARAMAGNETISM IN METALLIC SYSTEMS WITH LARGE ANGULAR MOMENTA

We demonstrate that the field induced spin and orbital moments in paramagnetic metals in general are parallel, since the Zeeman energy overcomes the spin-orbit energy that is in favor of an antiparallel arrangement when the electronic shell is less than half-filled. In the early actinides, however, the spin-orbit energy becomes sufficiently strong to approach the border where the moments can couple antiparallel. This results in peculiar magnetic states for α-Pu and some uranium compounds, where the spin moments are antiparallel to the applied field and the magnetic response dominated by the orbital character, and consequently these systems display unusual spin densities and magnetic form factors.

Field-induced magnetism in actinide systems

Abstract We demonstrate that the field-induced spin and orbital moments in paramagnetic metals in general are parallel, regardless of the filling of the electronic shell. The early actinides, however, approach the border where the moments go antiparallel. This results in peculiar magnetic states for α-Pu and some uranium compounds, where the spin moments are antiparallel to the applied field and the magnetic response is dominated by the orbital contribution, and consequently these systems display unusual spin densities and magnetic form factors.

Calculations of cyclotron orbit areas, effective masses and g-factors for the alkali metals

Band structures, cyclotron orbit areas, effective masses and g-factors for all the alkali metals have been calculated with the LMTO method. The magnetic field was treated with first order perturbation theory. Detailed comparisons with experimental data, wherever available, show a satisfactory agreement for all these quantities. The Stoner factor was found to be near 1.6 in all the alkali metals.

Self-consistent band structure calculations including external magnetic fields

Abstract The band structures for Pd and Pt in external magnetic fields have been calculated, using the LMTO-ASA method, including spin-orbit coupling, a Zeeman operator, and an exchange-correlation potential, enhancing the Zeeman splitting. Total cyclotron orbit g factors, spin and orbital components, and enhancement factors have been calculated for Γ6, X4 and α5 orbits and are compared with experimental values derived from the spin splitting factor obtained in de Haas-van Alphen measurements. The agreement in anisotropic behaviour as well as in total susceptibility is good, indicating that this model covers the effects which modify the energy levels of conduction electrons in an external magnetic field.