Cyclic four-spin exchange on a two-dimensional square lattice: Possible applications in high- T c superconductors
1989; American Physical Society; Volume: 39; Issue: 4 Linguagem: Inglês
10.1103/physrevb.39.2299
ISSN1095-3795
Autores Tópico(s)Magnetic properties of thin films
ResumoIn the planar Cu${\mathrm{O}}_{2}$ square lattice of new superconductors, the small energy difference of conducting holes between Cu and O sites, compared to the relatively large on-site energy for double occupancy, might favor cyclic four-hole exchange via intermediate O sites rather than superexchange processes, as in solid $^{3}\mathrm{He}$. The properties of the four-spin exchange and Heisenberg Hamiltonians are compared in two dimensions through exact diagonalization on small clusters up to 18 spins. Four-spin exchange could explain the large inelasticity observed in neutron and two-magnon Raman spectroscopy, and resolve some discrepancies between exchange frequencies deduced from Raman and susceptibility data.
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