Agenda

Prochain séminaire LANEF/Matériaux Quantiques :

Jeudi 21 mars 2024 à 14h00

Ludovic Jaubert (LOMA, Bordeaux)

“ A story about skyrmions, spin liquids and topological quantum Hall effects “

Pour accéder à ce séminaire :

Institut Néel CNRS, Bâtiment K, Salle Rémy Lemaire  (K223)

Résumé : Skyrmions are of interest both from a fundamental and technological point of view, as potential information carriers. In this colloquium, we will first provide a general introduction to skyrmions: how do they form in some specific magnetic systems, why do they crystallise, and why are people excited about them ?
One challenge concerns their manipulation though, especially at high temperature. Here we will propose a mechanism allowing for the manipulation of their density [1,2]. More precisely we will explain, based on simple stat-mech arguments and Monte Carlo simulations, how to use a spin liquid as an entropic buffer in order to impose a vacuum of skyrmions at high temperature. As a result, the temperature becomes a knob to tune the skyrmion density from a crystal, to a dense liquid and a diluted gas. And with this additional knob in hand, we find at high magnetic field a novel type of topological spin glass made of zero- and one-dimensional topological defects.
Finally we will couple the system to itinerant electrons, where the complex magnetic textures of skyrmions and of the spin liquid provide an effective magnetic field, inducing a topological quantised Hall effect to the electrons [2,3].

[1] H.D. Rosales, F.A. Gómez Albarracín, P. Pujol & L.D.C. Jaubert, Phys. Rev. Lett. 130, 106703 (2023)
[2] F.A. Gómez Albarracín, H.D. Rosales, M. Udagawa, P. Pujol & L.D.C. Jaubert, Phys. Rev. B 109, 064426 (2024)
[3] M. Udagawa, F.A. Gómez Albarracín, H.D. Rosales, P. Pujol & L.D.C. Jaubert (in preparation)

Les organisatrices :

Elsa Lhotel (elsa.lhotel@neel.cnrs.fr)
Florence Levy-Bertrand (florence.levy-bertrand@neel.cnrs.fr)