Electronic and magnetic properties of strongly correlated systems

Technical Report · Tue Aug 06 04:00:00 EDT 1991

OSTI ID:5265107

Leung, Tsan-Chuen

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 and are discussed in view of experiments in La{sub 2}CuO{sub 4}. In the calculation for La{sub 2}CuO{sub 4}, the d{sup 9} configuration is maintained by constraining the d{sub x{sup 2}-y{sup 2}} orbital to have exactly one hole. The Cu projected 3d density of states is compared with XPS data which slow 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 La{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. All these results indicate the local spin density functional approximation does not give correct solutions for these materials. To go beyond the LSDA, we study 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 approximation, is presented. The results are compared with those of the Hartree-Fork approximation, the Hubbard I approximation, and Quantum Monte Carlo simulation.

• Research Organization: Ames Lab., IA (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 5265107
• Report Number(s): IS-T-1545; ON: DE91018205
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
656100* -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANGULAR MOMENTUM
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CORRELATIONS
ELECTRON CORRELATION
ENERGY LEVELS
FERMI LEVEL
FERROMAGNETISM
FORM FACTORS
GROUND STATES
HARTREE-FOCK METHOD
HIGH-TC SUPERCONDUCTORS
LANTHANUM COMPOUNDS
MAGNETIC PROPERTIES
MAGNETISM
MONTE CARLO METHOD
OXIDES
OXYGEN COMPOUNDS
PARTICLE PROPERTIES
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SCANDIUM COMPOUNDS
SPIN
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS