Competition of the Coulomb and hopping based exchange interactions in granular magnets

  title={Competition of the Coulomb and hopping based exchange interactions in granular magnets},
  author={O. G. Udalov and Igor S. Beloborodov},
  journal={Physical Review B},
We study exchange coupling due to the interelectron Coulomb interaction between two ferromagnetic grains embedded into insulating matrix. This contribution to the exchange interaction complements the contribution due to virtual electron hopping between the grains. We show that the Coulomb and the hopping based exchange interactions are comparable. However, for most system parameters these contributions have opposite signs and compete with each other. In contrast to the hopping based exchange… 

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