• Séminaire nano-électronique quantique
• Personne à contacter : Robert Whitney ()
• Lieu : Salle Rémy Lemaire K223, Institut Néel

Résumé :

In experimental measurements the noise is not necessarily a complication and from it one can extract valuable information regarding its sources. Spin noise spectroscopy (SNS) is a powerful technique to get information about dynamics of various systems (atomic gases, conduction electrons, localized states in semiconductors…) based on their spin fluctuations. As powerful as the technique is, SNS only addresses time spin correlations, but not spatial correlations. Thus valuable informations on spin transport or many-body spin interactions are missed.

In this seminar, I shall start with an introduction to SNS from the principles to applications. Then I will present recent advances we made in developing an all-optical probe of spatiotemporal spin fluctuations based on a new SNS approach (1). This new technique gives access to spatial correlations and spin motion. We thus investigated electron spin dynamics in CdTe by measuring simultaneously the electron spin relaxation rate and the spin diffusion constant. In addition, the sensitivity of the SNS allows us to observe the effect of the local nuclear field on the evolution of the electron spin and to estimate the electron spin correlation time on a given donor site. We then face to an unprecedented puzzle we hope to solve.

(1) S. Cronenberger, C. Abbas, D. Scalbert and H.Boukari, Phys. Rev. Lett. 123 017401 (2019)

• Séminaire LPMMC
• Personne à contacter : Vincent Rossetto ()
• Lieu : Salle de lecture 2, maison des Magistères

Résumé : The Laughlin wave function is at the basis of the current understanding of the fractional quantum Hall effect, nevertheless, many of its fundamental properties are yet to be understood. I will present a model for its response, within Laughlin's ansatz, to variations of the external potential and of the long-range part of the interparticle interaction. Our main result is that the minimal energy within Laughlin's approximation is asymptotically attained, in the large particle number limit, by states exhibiting uncorrelated quasi-holes on top of the Laughlin wave function. This is a joint project with Nicolas Rougerie.

• Séminaire nano-électronique quantique
• Personne à contacter : "Benjamin Sacépé" ()
• Lieu : Salle Rémy Lemaire K223, Institut Néel