| Автор | J H V J Brabers |
| Автор | F Walz |
| Автор | H Kronmüller |
| Дата выпуска | 2000-06-26 |
| dc.description | The role of the band structure in the Verwey transition in magnetite (Fe<sub>3</sub>O<sub>4</sub>) has been analysed within the framework of an exactly solvable two-band model based on an effective interionic Coulomb potential splitting the 3d band of the t<sub>2g</sub> electrons. The model predicts an instability of the Verwey order below a certain ratio β/W of the Coulomb interaction parameter β and the bandwidth W. This instability can be understood in terms of a clear physical picture showing the impossibility of constructing a self-consistent ordered charge distribution in this case. A resemblance to the Cullen-Callen criterion is evident. It is shown as well that the influence of the band structure on the Verwey temperature vanishes rapidly when β/W increase beyond its critical value. Band-structure effects do provide an explanation, however, for the discontinuity in the Verwey temperature as a function of the concentration of cation dopants or the oxygen stoichiometry, which marks the transition from a first- to a second-order Verwey transition. In this respect, the model reproduces the experimental data quantitatively. Fits obtained by application of the model yield values of 0.037-0.04 eV for the Coulomb gap and 0.012-0.014 eV for the bandwidth. The obtained values of the bandwidth are typical for a strongly localized electron system and support a polaronic band picture. |
| Формат | application.pdf |
| Издатель | Institute of Physics Publishing |
| Название | The influence of a finite bandwidth on the Verwey transition in magnetite |
| Тип | paper |
| DOI | 10.1088/0953-8984/12/25/308 |
| Electronic ISSN | 1361-648X |
| Print ISSN | 0953-8984 |
| Журнал | Journal of Physics: Condensed Matter |
| Том | 12 |
| Первая страница | 5437 |
| Последняя страница | 5452 |
| Аффилиация | J H V J Brabers; Max-Planck Institut für Metallforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany |
| Аффилиация | F Walz; Max-Planck Institut für Metallforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany |
| Аффилиация | H Kronmüller; Max-Planck Institut für Metallforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany |
| Выпуск | 25 |
