title: Measurement of coherence decay in GaMnAs using femtosecond four-wave mixing.
abstract: The application of femtosecond four-wave mixing to the study of fundamental properties of diluted magnetic semiconductors ((s,p)-d hybridization, spin-flip scattering) is described, using experiments on GaMnAs as a prototype III-Mn-V system.  Spectrally-resolved and time-resolved experimental configurations are described, including the use of zero-background autocorrelation techniques for pulse optimization.  The etching process used to prepare GaMnAs samples for four-wave mixing experiments is also highlighted.  The high temporal resolution of this technique, afforded by the use of short (20 fsec) optical pulses, permits the rapid spin-flip scattering process in this system to be studied directly in the time domain, providing new insight into the strong exchange coupling responsible for carrier-mediated ferromagnetism.  We also show that spectral resolution of the four-wave mixing signal allows one to extract clear signatures of (s,p)-d hybridization in this system, unlike linear spectroscopy techniques.   This increased sensitivity is due to the nonlinearity of the technique, which suppresses defect-related contributions to the optical response. This method may be used to measure the time scale for coherence decay (tied to the fastest scattering processes) in a wide variety of semiconductor systems of interest for next generation electronics and optoelectronics.
authors: Department of Physics and Atmospheric Science, Dalhousie University.
authors: Daniel
authors: D
authors: Webber
authors: Tristan
authors: T
authors: de Boer
authors: Murat
authors: M
authors: Yildirim
authors: Sam
authors: S
authors: March
authors: Reuble
authors: R
authors: Mathew
authors: Angela
authors: A
authors: Gamouras
authors: Xinyu
authors: X
authors: Liu
authors: Margaret
authors: M
authors: Dobrowolska
authors: Jacek
authors: J
authors: Furdyna
authors: Kimberley
authors: K
authors: Hall
mesh_terms: D001152:Arsenicals / Q000737:chemistry*; D005708:Gallium / Q000737:chemistry*; D008280:Magnetics; D008345:Manganese / Q000737:chemistry*; D055095:Optics and Photonics / Q000295:instrumentation / Q000379:methods; D012666:Semiconductors; D013057:Spectrum Analysis / Q000379:methods
chemical_list: D001152:Arsenicals; D008345:Manganese; D005708:Gallium