| Description: | [DPS Seminar] Prof. Rudolf A. Roemer (Department of Physics, University of Warwick) -- Resolution of the exponent puzzle for the Anderson transition in doped semiconductors |
| Date: | Wednesday, Mar 28, 2018 |
| Time: | 3 p.m. - 4 p.m. |
| Venue: | G02, Lecture Hall Complex |
| Details: | The Anderson metal-insulator transition (MIT) has long been studied, but there is still no agreement on its critical exponent ν when comparing experiments and theory. In this work we employ ab-initio methods to study the MIT in sulfur-doped silicon (Si:S) when the dopant concentration is increased. We use linear-scaling DFT to study model Si:S systems at realistic concentrations (e.g., a few impurities, in a large simulation cell). From the resulting ab-initio Hamiltonian, we build an effective tight-binding Hamiltonian for larger systems close to the critical concentration of the MIT. We characterize the MIT in Si:S via multifractal finite-size scaling and obtain estimates of the phase diagram and ν. Our results suggest a possible resolution of the long-standing exponent puzzle due to the interplay between conduction and impurity states. |
| Calendar: | Seminar Calendar (entered by anandamohan) |