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Spin-polarized Mn2+ emission from Mn-doped colloidal nanocrystals
Ranjani Viswanatha1, Jeffrey M Pietryga, Victor I Klimov
1Chemistry Division, Los Alamos National Laboratory, New Mexico 87545, USA.
Physical Review Letters
|September 10, 2011
Summary
Magnetophotoluminescence studies reveal unique magnetic properties in zero-dimensional (0D) diluted magnetic semiconductors (DMS) nanocrystals. Unlike other dimensionalities, their Mn(2+) emission remains strong and becomes circularly polarized under magnetic fields.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Diluted Magnetic Semiconductors (DMS) exhibit unique magnetic and optical properties.
- Quantum confinement in nanomaterials significantly alters electronic and optical behavior.
- Understanding Mn(2+) ion behavior in confined DMS is crucial for spintronic applications.
Purpose of the Study:
- To investigate magnetophotoluminescence of strongly quantum-confined 0D DMS nanocrystals.
- To explore the influence of quantum confinement on Mn(2+) ion optical transitions.
- To analyze the magnetic field effects on emission properties in Mn(2+)-doped ZnSe/CdSe nanocrystals.
Main Methods:
- Magnetophotoluminescence spectroscopy was employed.
- Studies were conducted on Mn(2+)-doped ZnSe/CdSe core-shell colloidal nanocrystals (0D DMS).
- Comparison with 3D, 2D, and 1D DMS materials was performed.
Main Results:
- The yellow emission band (d-d transitions) of Mn(2+) ions was not suppressed by magnetic fields.
- Circular polarization of Mn(2+) emission was observed, tracking Mn(2+) magnetization.
- A significant energy splitting in circularly polarized emission scaled with exciton-Mn sp-d coupling, tunable by nanocrystal size.
Conclusions:
- Strong quantum confinement in 0D DMS nanocrystals profoundly influences magnetic ion excitation and emission.
- Observed phenomena differ markedly from bulk, quantum well, and quantum wire DMS counterparts.
- Tunable magnetic-exciton coupling in these nanocrystals offers potential for novel spintronic devices.
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