Noncollinear cluster magnetism in the framework of the Hubbard model

Article

关键词: SPIN-DENSITY-WAVE;    SURFACE ELECTRONIC-STRUCTURE;    TRANSITION-METAL CLUSTERS;    SMALL VANADIUM CLUSTERS;    SMALL IRON CLUSTERS;    FINITE TEMPERATURES;    FE;    CHROMIUM;    STATE;    C-60;   

DOI  :  10.1103/PhysRevB.60.6121

来源: SCIE

【 摘 要 】

Noncollinear magnetic states in clusters having N less than or equal to 43 atoms are studied by using the single-band Hubbard Hamiltonian within the fully unrestricted Hartree-Fock (UHF) approximation. The spin and charge degrees of freedom [(S) over right arrow(l)] and [n(l)] at every cluster atom are treated as independent variables. A variety of qualitatively different self-consistent solutions is obtained as a function of cluster size, structure, number of valence electrons v, 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 antiferromagneticlike or ferromagneticlike 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. [S0163-1829(99)06131-7].

【 授权许可】

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