Electronic and magnetic properties of strongly correlated systems

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1991

OSTI ID:5526658

Leung, Tsanchuen

Self-consistent, spin-polarized calculations are performed for Sc{sub 2}CuO{sub 4}, La{sub 2}CuO{sub 4} with constrained d{sup 9} configuration, and La{sub 2}NiO{sub 4}. For Sc{sub 2}CuO{sub 4}, both ferromagnetic and antiferromagnetic ground states are investigated and found to be unstable. Magnetic form factors are calculated for La{sub 2}CuO{sub 4}, and D{sup 9} configuration is maintained by constraining the d{sub x{sup 2}{minus}y{sup 2}} orbital to have exactly one hole. The Cu projected 3d density of states is compared with XPS data which show the binding energy of the Cu states is lower than the results from standard band structure calculations. The Cu d states are treated as core states and no hybridization is considered. This results in the d density of states being too narrow compared with experiment and the difference indicates the degree of hybridization with the oxygen 2p states. For L{sub 2}NiO{sub 4}, only the antiferromagnetic ground state is investigated and found to be stable but with the local moment on Ni being too small compared with experiment. The magnetic form factor for the antiferromagnetic state is examined and discussed in view of experiments. To go beyond the LSDA, he studies the extended Hubbard model. A mean field calculation of the two dimensional one and three band Hubbard models based on a Mori-projection operator formalism, which is called the projection operator mean field (POMF) approximation, is presented. The results are compared with those of the Hartree-Fork (HF) approximation, the Hubbard I approximation, and Quantum Monte Carlo (QMC) simulations.

• Research Organization: Iowa State Univ. of Science and Technology, Ames, IA (United States)
• OSTI ID: 5526658
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ANTIFERROMAGNETISM
BINDING ENERGY
CHALCOGENIDES
COMPARATIVE EVALUATIONS
COPPER COMPOUNDS
COPPER OXIDES
ELECTRICAL PROPERTIES
ENERGY
ENERGY LEVELS
EVALUATION
FERROMAGNETISM
FORM FACTORS
GROUND STATES
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
MAGNETIC PROPERTIES
MAGNETISM
MATHEMATICAL MODELS
MEAN-FIELD THEORY
OXIDES
OXYGEN COMPOUNDS
PARTICLE PROPERTIES
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SCANDIUM COMPOUNDS
SCANDIUM OXIDES
TRANSITION ELEMENT COMPOUNDS