Letter abstract
Nature Materials 8, 35 - 40 (2009)
Published online: 14 December 2008 | doi:10.1038/nmat2342
Subject Categories: Semiconductors | Magnetic materials | Nanoscale materials
Tunable magnetic exchange interactions in manganese-doped inverted core–shell ZnSe–CdSe nanocrystals
David A. Bussian1,2, Scott A. Crooker3, Ming Yin1, Marcin Brynda4, Alexander L. Efros5 & Victor I. Klimov1,2
Magnetic doping of semiconductor nanostructures is actively pursued for applications in magnetic memory and spin-based electronics1, 2. Central to these efforts is a drive to control the interaction strength between carriers (electrons and holes) and the embedded magnetic atoms3, 4, 5. In this respect, colloidal nanocrystal heterostructures provide great flexibility through growth-controlled 'engineering' of electron and hole wavefunctions in individual nanocrystals6, 7. 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 Mn2+-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 used to manipulate carrier–Mn2+ wavefunction overlap and the sp–d exchange parameters themselves.
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
- Center for Integrated Nanotechnologies, Los Alamos, New Mexico 87545, USA
- National High Magnetic Field Laboratory, Los Alamos, New Mexico 87545, USA
- Department of Chemistry, University of California, Davis, California 95616, USA
- Naval Research Laboratory, Washington, District of Columbia 20375, USA
Correspondence to: Scott A. Crooker3 e-mail: crooker@lanl.gov
Correspondence to: Victor I. Klimov1,2 e-mail: klimov@lanl.gov
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