| Автор | P J Brown |
| Автор | A Y Bargawi |
| Автор | J Crangle |
| Автор | K-U Neumann |
| Автор | K R A Ziebeck |
| Дата выпуска | 1999-06-21 |
| dc.description | Polarized neutron scattering has been used to determine the changes in the distribution of unpaired electrons which take place in the martensitic transition in Ni<sub>2</sub>MnGa. Ni<sub>2</sub>MnGa is a ferromagnetic Heusler alloy which undergoes a reversible transition at about 220 K from a high temperature cubic phase to a low temperature tetragonal one. It has been suggested, on the basis of band structure calculations, that the structural phase transition is driven by a band Jahn-Teller distortion involving redistribution of electrons between 3d sub-bands of different symmetries. The results of the neutron scattering experiments show that the transition from the cubic to the tetragonal phase is accompanied by a transfer of magnetic moment from Mn to Ni. The unpaired electrons in the cubic phase have overall e<sub>g</sub> symmetry. In the tetragonal phase, the degeneracy of the e<sub>g</sub> and t<sub>2g</sub> bands is raised and the unpaired electrons are redistributed in such a way that the sub-bands based on orbitals extending towards the c-axis are preferentially occupied. Although the experimental moments differ in detail from those expected from band structure calculations, the change in symmetry of the magnetization distribution is consistent with a band Jahn-Teller origin for the phase transition. |
| Формат | application.pdf |
| Издатель | Institute of Physics Publishing |
| Название | Direct observation of a band Jahn-Teller effect in the martensitic phase transition of Ni<sub>2</sub>MnGa |
| Тип | paper |
| DOI | 10.1088/0953-8984/11/24/312 |
| Electronic ISSN | 1361-648X |
| Print ISSN | 0953-8984 |
| Журнал | Journal of Physics: Condensed Matter |
| Том | 11 |
| Первая страница | 4715 |
| Последняя страница | 4722 |
| Выпуск | 24 |
