Regensburg 2007 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 28: Transport - Poster Session
TT 28.52: Poster
Thursday, March 29, 2007, 14:00–17:45, Poster A
Probing Spin Precession by Noise Spectroscopy — •Matthias Braun1, Jürgen König1, and Jan Martinek2 — 1TPIII, Ruhr-Universität Bochum, 44780 Bochum, Germany — 2IMP, Polish Academy of Science, 60-179 Poznań, Poland
We theoretically discuss the possibility to observe electron-spin
precession by its imprint on the noise spectrum of a reference quantity.
A finite-frequency noise measurement of this reference quantity can
therefore be used as unorthodox electron-spin resonance experiment.
We review two different systems illustrating this idea.
1.) In a single-level quantum dot with
ferromagnetic leads, the spin noise is mapped on the current
noise by tunnel magnetoresistance [1]. The current-noise frequency spectrum
then reveals Larmor frequency and spin life time of the conduction
electrons. This transport experiment
is therefore equivalent to a single spin cw-ESR experiment.
2.) By sending laser light through selected semiconductor [2] or gas [3]
samples, one can observe a Faraday rotation of the polarization plane. In addition, the
spin fluctuations in the sample also lead to fluctuations of the Faraday
rotation. These fluctuations can again be measured, and used as ESR
experiment. It is even possible to realize Faraday-rotation fluctuation
experiments, which avoid some sources of inhomogeneous line broadening [4].
[1] M. Braun et al., Phys. Rev. B 74, 075328 (2006).
[2] M. Oestreich et al., Phys. Rev. Lett. 95, 216603 (2005).
[3] S. A. Crooker et al., Nature 431, 49 (2004).
[4] M. Braun et al., cond-mat/0601607.