Noncollinear cluster magnetism in the framework of the Hubbard model

Abstract

Noncollinear magnetic states in clusters are studied by using the single-band Hubbard Hamiltonian. The unrestricted Hartree-Fock (UHF) approximation is considered without imposing any symmetry constraints neither to the size or orientation of the local magnetic moments $<{\vec{S}}_l>$ nor to the local charge densities $<n_l>$. A variety of qualitatively different selfconsistent solutions is obtained as a function of cluster size, structure, number of valence electrons $\nu$ and Coulomb interaction strength $U/t$. This includes inhomogeneous density distributions, paramagnetic solutions, magnetic solutions with collinear moments and noncollinear spin arrangements that show complex antiferromagnetic and ferromagnetic-like orders. The environment dependence of the magnetic properties is analyzed giving emphasis to the effects of antiferromagnetic frustrations in compact structures close to half-band filling. Electron correlation effects are quantified by comparing UHF and exact results for the local magnetic moments, total spin, spin-correlation functions and structural stability of 13-atom clusters. Goals and limitations of the present noncollinear approach are discussed.

Latex, two-colums 13 pages, 9 figures

References in corpus (3)

• Magnetic Properties of Undoped $C_{60}$
• Generalized spin density wave state of the Hubbard model on the C12 and C60 clusters
• Non-collinear magnetism in Al-Mn topologically disordered systems

Cited by in corpus (6)

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• Noncollinear and noncoplanar magnetic order in the extended Hubbard model on anisotropic triangular lattice
• Hubbard pair cluster with elastic interactions. Studies of thermal expansion, magnetostriction and electrostriction
• Electron correlations in a C${}_{20}$ fullerene cluster: A lattice density-functional study of the Hubbard model