Spin fluctuations and covalence in neutron Bragg scattering from YBa sub 2 Cu sub 3 O sub 6 and La sub 2 CuO sub 4
- Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824 (USA) Center for Fundamental Materials Research, Michigan State University, East Lansing, Michigan 48824 (USA)
A puzzle is pointed out concerning the low-temperature behavlor of La{sub 2}CuO{sub 4} and YBa{sub 2}Cu{sub 3}O{sub 6,} the insulating parents'' of the high-{ital T}{sub {ital c}} superconductors, and indicate a possible solution. The measured ordered magnetic moment is about 0.64 {mu}{sub {ital B}} per Cu, in agreement with the value calculated on the basis of the Heisenberg Hamiltonian. But this calculation is within a nearly purely ionic or localized picture of the Cu {ital d} hole, the reduction from 1.1 {mu}{sub {ital B}} ({ital g}{approx}2.2) being entirely due to spin fluctuations. Thus the almost perfect agreement leaves no room for the moment reduction due to covalence or 3{ital d}-2{ital p} hybridization, expected to be large in these oxides. A possible explanation might lie in the fact that an ostensibly symmetry-based argument relating the calculated moment (in the symmetry-unbroken state) to that measured is not valid, as has recently been shown.
- OSTI ID:
- 5623250
- Journal Information:
- Journal of Applied Physics; (USA), Vol. 69:8; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BARIUM OXIDES
NEUTRON DIFFRACTION
COPPER OXIDES
LANTHANUM OXIDES
YTTRIUM OXIDES
COVALENCE
HYBRIDIZATION
MAGNETIC MOMENTS
MAGNETIC PROPERTIES
SYMMETRY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COHERENT SCATTERING
COPPER COMPOUNDS
DIFFRACTION
LANTHANUM COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SCATTERING
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties