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Theory of Spin-charge-orbital States in the Frustrated System RFe2O4

Published online by Cambridge University Press:  26 February 2011

Sumio Ishihara
Affiliation:
ishihara@cmpt.phys.tohoku.ac.jp, Tohoku University, Department of Physics, Aramaki, Aoba, Sendai, 980-8578, Japan, +81-22-795-6436, +81-22-795-6436
Makoto Naka
Affiliation:
naka@cmpt.phys.tohoku.ac.jp, Tohoku University, Department of Physics, Aramaki, Aoba, Sendai, 980-8578, Japan
Aya Nagano
Affiliation:
aya@cmpt.phys.tohoku.ac.jp, Tohoku University, Department of Physics, Aramaki, Aoba, Sendai, 980-8578, Japan
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Abstract

Electronic structure in multiferroic compound RFe2O4. is studied theoretically. We suggest that orbital degree of freedom in a Fe2+ ion is active. The effective Hamiltonian for spin, charge and orbital degrees of freedom is derived. Numerical analyses with the multi-canonical Monte-Carlo simulation show that the electric polarization is attributed to the charge order with momentum (1/3, 1/3). A magnitude of the polarization is enhanced around the magnetic ordering temperature due to the coupling between spin and charge. Conventional orbital order is not expected from the numerical calculation. We discuss possible orbital state at low temperatures.

Type
Research Article
Copyright
Copyright © Materials Research Society 2007

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References

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