research


Understanding pulsed EDMR experiments

Pulsed electrically detected magnetic resonance spectroscopy (pEDMR) is an only recently demonstrated method that allows the detection of coherent electron spin motion by measuring electric current after a coherent (pulsed) spin resonant excitation.

The observable of pEDMR (the current is controlled by spin-selection rules) experiments is different from conventional pulsed electron spin resonance (pESR) experiments (an x- and/or y-polarization component). Therefore, the signals of spins observed with pEDMR may differ from those with pESR. We have been investigating these differences theoretically in a collaboration with Sergei Baranovskii from Philipps Universitaet in Marburg and Klaus Lips from Helmholtz-Zentrum Berlin fuer Materialien und Energie (formerly Hahn- Meitner-Institut). One of the remarkable insights gained in these studies is that spin-beat oscillations in spin pairs can be much more pronounced in pEDMR signals in comparison to pESR.




Simulated data of an electrically detected Rabi nutation as a function of the applied microwave frequency in presence of a constant magnetic field. The data show pronounced signals at two frequencies that correspond to the electron spin resonances of the charge carriers within the charge carrier pairs.




a) Three-dimensional color plots of the Fourier transform of a simulated pEDMR transient nutation experiment as a function of the difference of the microwave frequency to the average of the spin pairs Larmor frequencies. One can see the presence of different nutation frequencies for different Larmor separations within the charge carrier pairs indicative of the dominant beat oscillation.

Our recent results on this topic:

J. Behrends*, K. Lips and C. Boehme
Observation of precursor pair formation of recombining charge carriers Phys. Rev. B
80, 045207 (2009).  http://dx.doi.org/10.1103/PhysRevB.80.045207
(Editors' suggestion)

C. Michel, A. Gliesche, S.D. Baranovskii*, K. Lips, F. Gebhard and C. Boehme* , The influence of disorder on electrically and optically detected electron spin nutation, Phys. Rev. B, 79, Brief Reports, 05221 (2009). http://dx.doi.org/10.1103/PhysRevB.79.052201


A. Gliesche, C. Michel, V. Rajevac, K. Lips, S.D. Baranovskii, F. Gebhard and C. Boehme* , Effect of exchange coupling on coherently controlled spin-dependent transition rates, Phys. Rev. B, 77, 245206 (2008). http://dx.doi.org/10.1103/PhysRevB.77.245206 also on arXiv:cond-mat/0801.1304 (2008). http://lanl.arxiv.org/abs/0801.1304


V. Rajevac, C. Boehme*, C. Michel, A. Gliesche, K. Lips, S. D. Baranovski, P. Thomas,
Transport and recombination through weakly coupled localized spin pairs in semiconductors during coherent spin excitation , Phys. Rev. B 74, 245206 (2006). http://dx.doi.org/10.1103/PhysRevB.74.245206
also on arXiv – cond-mat: 0607627  (2006). http://lanl.arxiv.org/abs/cond-mat/0607627


Principal Investigator: Christoph Boehme, Department of Physics and Astronomy, University of Utah,
115 S 1400 E, Salt Lake City, UT 84112-0830, phone 801.581.6806 fax 801.581.4801,
email: boehme@physics.utah.edu.
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