Low-temperature ferromagnetism in a weakly doped Hubbard magnet
| Autor: | Zubov, E. E. |
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| Rok vydání: | 2010 |
| Předmět: | |
| Zdroj: | Ukrainian Journal of Physics, 2009, Vol. 54, no. 1-2, pp. 207-215 |
| Druh dokumentu: | Working Paper |
| Popis: | In the framework of the diagrammatic method with self-consistent field, the maximum on the temperature dependence of the susceptibility of a weakly doped narrow-band Hubbard magnet below the Curie temperature $T_{\rm C}$ is predicted. By numerical calculations, it is proved that it appears at small hole concentrations $n_{h}$. In this case, the temperature dependence of the magnetization $M$($T$) has a typical Fermi-like shape with the point of inflection at a temperature $T_{\rm inf}$. The approximate solution of the system of equations for the mean spin and the chemical potential gives the Schottky susceptibility typical of a two-level system with a gap of order of $n_{h}(1-n_{h})W$, where W is the bandwidth. This behavior reflects the existence of two subbands with up- and down-spins. It may be observed experimentally in the surface layers of oxide metal nanoparticles with narrow bands and a weak oxygen nonstoichiometry. Comment: 4 pages, 4 figures; http://www.ujp.bitp.kiev.ua |
| Databáze: | arXiv |
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