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キーワード:
exchange integrals; cuprates; vanadates
要旨:
We propose a method of the calculation of effective exchange coupling constants between the magnetic ions in transition metal oxides based on the mapping of the energy of noncollinear spin-spiral states calculated with the LDA + U method to the mean-field solutions of the effective spin Hamiltonian. The approach is applied to Sr2CuO2Cl2 which can be described with good accuracy by a 2D Heisenberg model with only nearest- neighbor exchange. The same method is also used to determine the exchange constants in the charge ordered low-temperature phase of NaV2O5. (C) 2002 Elsevier Science B.V. All rights reserved.
