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Remanent zero field spin splitting of self-assembled quantum dots in a paramagnetic host
C Gould1, A Slobodskyy, D Supp
1Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
Physical Review Letters
|August 16, 2006
Summary
We observed spin splitting in quantum dots without a magnetic field, suggesting a magnetic polaron effect. This phenomenon in dilute magnetic semiconductors persists at higher temperatures due to electrical current feedback.
Area of Science:
- Condensed Matter Physics
- Semiconductor Nanostructures
- Spintronics
Background:
- Bulk II-VI dilute magnetic semiconductors are typically paramagnetic.
- Quantum dots offer unique properties for studying spin interactions.
- Magnetic polarons are theoretical constructs involving localized magnetic moments mediated by carriers.
Purpose of the Study:
- To investigate spin splitting in CdSe quantum dots within a magnetic semiconductor barrier.
- To explore the formation and properties of magnetic polarons in such systems.
- To determine the temperature dependence of the observed spin splitting.
Main Methods:
- Resonant tunneling experiments were conducted on CdSe self-assembled quantum dots.
- The quantum dots were embedded in a (Zn,Be,Mn)Se barrier, a dilute magnetic semiconductor.
- Measurements were performed to detect spin splitting at zero magnetic field.
Main Results:
- A finite spin splitting was observed at zero magnetic field.
- This effect suggests the formation of a magnetic polaron, where carriers mediate ferromagnetic interactions between Mn ions.
- The spin splitting was observable up to relatively high temperatures.
Conclusions:
- The experiment demonstrates a novel zero-field spin splitting in quantum dots, potentially due to a magnetic polaron effect.
- The observed phenomenon challenges the typical paramagnetic nature of bulk II-VI dilute magnetic semiconductors.
- The temperature stability is tentatively attributed to a current-feedback mechanism, aligning with theoretical predictions.
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