ON THE CONTRIBUTION OF THE FERMI CONTACT TERM TO THE MAGNETIC FIELD AT THE NUCLEUS

Journal Article · Wed Mar 01 04:00:00 EST 1961 · Journal of Applied Physics (U.S.)

DOI:https://doi.org/10.1063/1.2000370· OSTI ID:4057422

Watson, R E; Freeman, A J

The dominant source of the effective magnetic field at the nuclei in ferromagnets apparently comes from the Fermi contact contribution of the s electrons in the core. This contribution was investigated for transition element atoms and ions by means of a series of spin polarized HartreeFock calculatlons. Calculations were done for both freeatom and crude crystalline environments. The sensitivity of the 3s electrons to 3d behavior was found to contribute to large differences in calculated effective fields. The differences between core polarizations in metals and ions are discussed with the use of a model for metallic iron (i.e., a 3d/sup 8/ configuration) which is more consistent with neutron diffraction and energy band results than the free atom 3d/sup 8/ state (the spin polarized 3d/sup 8/ calculation shows an expanded 3d charge density but an almost unchanged spin density relative to the 3d/sup 8/ results). The resultant (negative) increase in the effective field is not, however, large enough to overcome the positive contributions of the outer electrons so that although a net negative field is found it is not large enough in magnitude to agree with the Mossbauer measurements. A parallel calculation by Goodings and Heine, based on an artificially expanded 3d charge and spin densities, ls also found to be similarly deficient. Their model is discussed and shown to be incompatible with neutron experiments and enengy band calculations. (auth)

• Research Organization: AVCO, RAD, Wilmington, Mass.; and Massachusetts Inst. of Tech., Cambridge
• Sponsoring Organization: USDOE
• NSA Number: NSA-15-014872
• OSTI ID: 4057422
• Journal Information: Journal of Applied Physics (U.S.), Journal Name: Journal of Applied Physics (U.S.) Vol. Vol: 32: No. 3, Suppl.; ISSN JAPIA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ATOMS
BETA DECAY
CONFIGURATION
CRYSTALS
DENSITY
DIFFRACTION
ELECTRIC CHARGES
ELECTRONS
ENERGY
ENERGY LEVELS
ENVIRONMENT
FERMI INTERACTION
FERROMAGNETIC MATERIALS
FIELD THEORY
FOCK METHOD
HARTREE-FOCK METHOD
INTERACTIONS
IONS
IRON
MAGNETIC FIELDS
MEASURED VALUES
METALS
MOESSBAUER EFFECT
NEUTRONS
NUCLEI
PHYSICS
QUANTITY RATIO
SENSITIVITY
SPECTRA
SPIN
TRANSITION METALS
WEAK INTERACTIONS