Noncollinear Magnetic Structures in Small Compact Clusters
We investigate the properties of complex magnetic structures in small compact clusters including noncollinear arrangements of local magnetic moments, spin density waves and charge density waves. The Hubbard Hamiltonian is solved within the unrestricted Hartree-Fock (UHF) approximation without imposing any symmetry constraints neither to the size or orientation of the local magnetic moments nor to local charge densities. For icosahedral and fcc-like clusters having N = 13 atoms, and for band-fillings close to half-band, the most stable solutions of UHF equations are discussed as a function of the Coulomb interaction strength U/t. The role of noncollinear arrangements of spins in the ground-state magnetic behavior is analyzed. The high connectivity of these compact clusters and the tendency to antiferromagnetic order between nearest-neighbors spins close to half-band filling results in magnetic frustrations and in remarkable noncollinear-spin solutions.
KeywordsHubbard Model Nearest Neighbor Magnetic Order Charge Density Wave Local Magnetic Moment
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