A. J. Freeman

Electronic structure and magnetism of CuNi coherent modulated structures

The electronic structure and magnetism of coherent modulated structures of CuNi for varying numbers of Cu and Ni layers modulated along [111] and [100] directions has been determined theoretically by means of self‐consistent spin polarized LMTO energy band studies and compared with experiment and with theoretical results separately obtained for bulk fcc and tetragonally distorted Ni metal. The magnetic moments in the Ni layers in CuNi are found to be reduced relative to that of fcc Ni indicating that the enhanced magnetism deduced from earlier ferromagnetic resonance observations must arise from other sources. These predictions have been confirmed recently by direct magnetization and neutron magnetic scattering studies.

Theory of the two peak photoemission spectra in cerium compounds

Considerable controversy has centered on the origin of the observed two peak structure in photoemission from Ce compounds. We report results of theoretical studies of the Ce pnictides using a model based on competing screening mechanisms. It is assumed that the peak near EF arises from complete screening of the 4f hole via repopulation of the f orbital on the hole site so its contribution to the spectrum follows the ground state density of states. The second peak 2–3 eV lower in energy is viewed as being due to a poorly screened f-hole. This screening process is studied by means of self-consistent LAPW supercell calculations. In CeSb we find a peak separation of 2.71 eV compared to an experimental value of 2.5 eV, whereas in CeP we find a separation of 2.47 eV compared to 2.4 eV experiment. The poorly screened peak results primarily from d-orbital screening of the hole.

Electronic structure and magnetic properties of CeAl2

Self‐consistent electronic energy band calculations have been performed utilizing the LMTO method for CeAl2 in assumed paramagnetic, induced ferromagnetic, and antiferromagnetic states. The paramagnetic Ce f band is roughly 1 eV wide and is located primarily above the Fermi energy with a leading edge extending down and producing a very high density of states at the Fermi energy. The induced ferromagnetic calculation shows large enhancement of the field but appears to decay when the field is removed. We have approximated the observed antiferromagnetic structure by the simple two sublattice form which does not enlarge the unit cell. The f level density of states is sharply narrowed in this state. Further, the state is self‐consistently stable; after the fictitious driving field is removed, it does not decay away and results in a moment of 0.88 μB in good agreement with the neutron results of Barbara et al.

Supercell band structure calculations of the two peak photo- and inverse photoemission spectra in Ce and Pr compounds

Abstract We show that the two peak photoemission and inverse photoemission spectra in Ce and Pr compounds can be determined theoretically using a local density supercell approach with different channels to screen the 4f hole in photoemission and antiscreen the extra 4f electron in inverse photoemission.

Magnetic anisotropy of ferromagnetic Fe and Co thin films (invited) (abstract)

The observation of transition‐metal (TM) magnetic moments in thin films aligned perpendicular to the surface has focused theoretical and experimental attention on the origin of magnetic anisotropy in these exciting low‐dimensional materials. In this paper we report on a study of the magnetic anisotropy of Fe and Co thin films originating from the spin‐orbit interaction term of the fully relativistic Dirac equation. We employ a total energy second variation FLAPW method in which: (i) the electronic charge density is determined with the semirelativistic (no spin‐orbit) FLAPW method; (ii) relativistic eigenvalues are calculated via a variational procedure using the semirelativistic wave functions as basis. The magnetic anisotropy energy of free‐standing Fe(001) and Co(001) monolayers yields in‐plane orientation of the spin moment. Semirelativistic calculations determined the magnetic moments of 1Fe/1Au, 1Fe/1Ag, or 1Fe/1Pd−all (001) slabs; the results agree well with those of monolayer Fe on thicker substrat...

Electronic structure and itinerant magnetism in ZrZn2 and TiBe2

The electronic and magnetic structure of the Cl5 compounds ZrZn2 and TiBe2 has been determined by means of self‐consistent spin‐polarized LMTO band calculations. The spin‐densities and neutron magnetic form factors are compared with neutron scattering data for ZrZn1.9 and TiBe1.8Cu0.2. The moments are found to reside almost entirely on the Zr/Ti atoms, and are found to be 0.14 and 0.21 μB per formula unit respectively.