We present resistivity measurements of Mott insulator NiS2 single crystals after heat treatment. We find a strong increase of the low temperature resistivity that relaxes back towards the pristine behaviour over several days with a time constant of 45 h at room temperature. The low temperature resistivity has previously been shown to be dominated by surface conduction (Thio and Bennett, 1994 ). Consequently, the changes induced by heat treatment are attributed to changes of surface states. Our results suggest the creation of vacancies in the surface that are refilled from the bulk via atomic diffusion. We estimate a diffusion constant of D 1×10-10 m2 s-1 at room temperature. We identify sulphur vacancies as the most likely to form via oxidisation of sulphur forming volatile SO2 during heat treatment. Our results point towards these sulphur vacancies to be the source of surface state localisation in NiS2.
|Number of pages
|Journal of Magnetism and Magnetic Materials
|Published - 15 Feb 2016
|ICM2015: 20th International Conference on Magnetism - Palau de Congressos de Catalunya, Barcelona, Spain
Duration: 5 Jul 2015 → 10 Jul 2015
Bibliographical noteSpecial Issue: Proceedings of the 20th International Conference on Magnetism (Barcelona) 5-10 July 2015. Edited by José Rivas and Domique Givord.
- Mott insulator
- Surface state