Tunable magnetic exchange interactions in manganese-doped inverted core/shell ZnSe/CdSe nanocrystals
| Autor: | Bussian, David A., Crooker, Scott A., Yin, Ming, Brynda, Marcin, Efros, Alexander L., Klimov, Victor I. |
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| Rok vydání: | 2008 |
| Předmět: | |
| Zdroj: | Nature Materials v8, pp35-40 (2009) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1038/nmat2342 |
| Popis: | Magnetic doping of semiconductor nanostructures is actively pursued for applications in magnetic memory and spin-based electronics. Central to these efforts is a drive to control the interaction strength between carriers (electrons and holes) and the embedded magnetic atoms. In this respect, colloidal nanocrystal heterostructures provide great flexibility via growth-controlled `engineering' of electron and hole wavefunctions within individual nanocrystals. Here we demonstrate a widely tunable magnetic sp-d exchange interaction between electron-hole excitations (excitons) and paramagnetic manganese ions using `inverted' core-shell nanocrystals composed of Mn-doped ZnSe cores overcoated with undoped shells of narrower-gap CdSe. Magnetic circular dichroism studies reveal giant Zeeman spin splittings of the band-edge exciton that, surprisingly, are tunable in both magnitude and sign. Effective exciton g-factors are controllably tuned from -200 to +30 solely by increasing the CdSe shell thickness, demonstrating that strong quantum confinement and wavefunction engineering in heterostructured nanocrystal materials can be utilized to manipulate carrier-Mn wavefunction overlap and the sp-d exchange parameters themselves. Comment: To appear in Nature Materials; 18 pages, 4 figures + Supp. Info |
| Databáze: | arXiv |
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