Location: Room E

Lucien Besombes from Institut Néel, Grenoble, will talk on "Dynamics and optical control of an individual Mn spin in a semiconductor quantum dot". The abstract is below (and the .doc version with references is attached). Everybody is welcome.

Best regards

Yaroslav

Dynamics and optical control of an individual Mn spin in a semiconductor quantum dot

L. Besombes

CEA- CNRS team "Nanophysique et semiconducteurs", Institut Néel, CNRS & University Joseph Fourier, 38042, Grenoble, France.

The decrease of the structure size in semiconductor electronic devices and magnetic information storage devices has dramatically reduced the number of atoms necessary to process and store bit of information. Information storage on a single magnetic atom would be an ultimate limit. Diluted magnetic semiconductors systems combining high quality semiconductor structures and the magnetic properties of Mn atoms (S=5/2) are model systems for the study of these ultimate devices. The performance of such memory elements will be governed by the quantum fluctuations of the localized spins.

With the recent development of quantum dots doped with single Mn atoms, the optical probing of a single atomic spin in a solid state environment became possible using optical micro-spectroscopy techniques: The photon emitted or absorbed by a II-VI semiconductor Mn-doped quantum dot is directly related to the spin state of the Mn atom localized in the dot. This is due to the exchange interaction of an electron-hole pair and the Mn atom: the electron-hole pair acts as an effective magnetic field along the quantum dots’ growth axis that lifts up the degeneracy between the six (2S+1) Mn spin states. Depending on the Mn spin projection, the recombination of an injected e-h pair emits a photon with a given energy and polarization

In this talk, we will show how the photons emitted by an individual CdTe/ZnTe quantum dot containing a single Mn atom can be used to probe the dynamics of the Mn spin. We will also discuss how the resonant optical injection of spin polarized carriers can be a tool to control this localized spin. After a description of the spin structure of the system formed by the interaction between a controlled number of confined carriers and a localized Mn spin1,2 we will present photon correlation3 and time resolved optical pumping experiments4,5 on individual quantum dots allowing probing the dynamics of these few interacting spins.