Investigation of the Presence of Charge Order in Magnetite by Measurement of the Sprin Wave Spectrum

Journal Article · Sun Jan 01 04:00:00 EST 2006 · Physical Review B

DOI:https://doi.org/10.1103/PhysRevB.73.174409· OSTI ID:1042711

McQueeny, R. J. ^[1]; Yethiraj, Mohana ^[2]; Montfrooij, W. ^[3]; Garner, J. S. ^[4]; Metcalf, P. ^[5]; Honig, J. M. ^[6]

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1. Ames Laboratory
2. ORNL
3. University of Missouri, Columbia
4. Brookhaven National Laboratory (BNL)
5. Purdue University
6. University of Purdue

Inelastic neutron scattering results on magnetite (Fe{sub 3}O{sub 4}) show a large splitting in the acoustic spin wave branch, producing a 7 meV gap midway to the Brillouin zone boundary at q = (0,0,1/2) and {h_bar}{omega} = 43 meV. The splitting occurs below the Verwey transition temperature, where a metal-insulator transition occurs simultaneously with a structural transformation, supposedly caused by the charge ordering on the iron sublattice. The wavevector (0,0,1/2) corresponds to the superlattice peak in the low symmetry structure. The dependence of the magnetic superexchange on changes in the crystal structure and ionic configurations that occur below the Verwey transition affect the spin wave dispersion. To better understand the origin of the observed splitting, several Heisenberg models intended to reproduce the pair-wise variation of the magnetic superexchange arising from both small crystalline distortions and charge ordering were studied. None of the models studied predicts the observed splitting, whose origin may arise from charge-density wave formation or magnetoelastic coupling.

• Research Organization: Oak Ridge National Laboratory (ORNL); High Flux Isotope Reactor
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1042711
• Journal Information: Physical Review B, Journal Name: Physical Review B Journal Issue: 17 Vol. 73; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ACOUSTICS
BRILLOUIN ZONES
CHARGE DENSITY
CRYSTAL STRUCTURE
HEISENBERG MODEL
INELASTIC SCATTERING
IRON
MAGNETITE
NEUTRON DIFFRACTION
SPIN WAVES
SUPERLATTICES
SYMMETRY
TRANSITION TEMPERATURE