Quantensysteme

Advanced Seminar on Condensed Matter Physics

Sommersemester 2014

gehe zu Wintersemester 2014/2015

KIP SR 01.404
freitags 11:15

Vorträge
15.8.2014 11:15
Ioannis Stasinopoulos, Technische Universität München, Physik Department E10
KIP SB 02.107

Skyrmions are topologically stable spin textures with the spins pointing in all directions wrapping up a sphere. They emerge in chiral-magnets and arrange in a hexagonal lattice with typical lattice constants of several tens of nm. A detailed understanding of the collective spin excitations and damping mechanisms in these materials [1] is of great interest if one thinks about the application of the hexagonally ordered magnetic Skyrmion-lattice phase in spintronics and magnonics. We have used cryogenic broadband GHz spectroscopy based on a coplanar waveguide (CPW) and a vector network analyzer [2] to explore the magnetization dynamics across the entire magnetic phase diagrams of a metallic (MnSi), a semiconducting (Fe0.8Co0.2Si) and an insulating chiral magnet (Cu2OSeO3). The CPW excites and simultaneously probes the spin excitations in the helimagnets [3]. For the metallic, semiconducting, and insulating chiral magnets the spin excitations occur at different GHz frequencies depending on the material and applied magnetic field. Still we provide a unified quantitative account of their field dependent resonance frequencies across the whole magnetic phase diagram. The universal behavior of these excitations sets the stage for purpose-designed applications based on the resonant response of chiral magnets with tailored electric conductivity offering an unprecedented freedom for integration with electronics.

Financial support by the DFG via SFB/TRR80 and the German excellence cluster “Nanosystems Initiative Munich (NIM)” is acknowledged.

[1] Y. Onose et al., PRL, 109, 037603 (2012)
[2] S. S. Kalarickal et al., JAP, 99, 093909 (2006)
[3] T. Schwarze et al., unpublished