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News 05.07.2025
New publication: Electric-Field-Tunable Spin−Orbit Gap in a Bilayer Graphene/WSe2 Quantum Dot

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News 04.04.2014

New publication: Unambiguous determination of spin dephasing times in ZnO

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Phys. Status Solidi B (2014)
Time-resolved magneto-optics is a well-established optical pump–probe technique to generate and to probe spin coherence in semiconductors. By this method, spin dephasing times T2* can easily be determined if their values are comparable to the available pump–probe delays. If T2* exceeds the laser repetition time, however, resonant spin amplification (RSA) can equally be used to extract T2* image. We demonstrate that in ZnO these techniques have several tripping hazards resulting in deceptive values for T2* and show how to avoid them. We show that the temperature dependence of the amplitude ratio of two separate spin species can easily be misinterpreted as a strongly temperature-dependent T2* of a single spin ensemble, while the two spin species have T2* values, which are nearly independent of temperature. Additionally, consecutive pump pulses can significantly diminish the spin polarization, which remains from previous pump pulses. While this barely affects T2* values extracted from delay line scans, it results in seemingly shorter inline image values in RSA.

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