Department Colloquium: Topological Spin Dynamics for GreenIT
- Date: –12:00
- Location: Ångströmlaboratoriet, Lägerhyddsvägen 1 Häggsalen
- Lecturer: Mathias Kläui, Johannes Gutenberg Universität, Mainz
- Contact person: Jan-Erik Rubensson
In our information-everywhere society IT is a major player for energy consumption. Novel spintronic devices can play a role in the quest for GreenIT if they are stable and can transport and manipulate spin with low power. Devices have been proposed, where switching by energy-efficient approaches, such as spin-polarized currents is used , for which we develop new highly spin-polarized materials and characterize the spin transport using THz spectroscopy .
Firstly to obtain ultimate stability of states, topological spin structures that emerge due to the Dzyaloshinskii-Moriya interaction (DMI) at structurally asymmetric interfaces, such as chiral domain walls and skyrmions with enhanced topological protection can be used [3-5]. We have investigated in detail their dynamics and find that it is governed by the topology of their spin structures . By designing the materials, we can even obtain a skyrmion lattice phase as the ground state of the thin films .
Secondly, for ultimately efficient spin manipulation, we use spin-orbit torques, that can transfer more than 1ħ per electron by transferring not only spin but also orbital angular momentum. We combine ultimately stable skyrmions with spin orbit torques into a skyrmion racetrack device , where the real time imaging of the trajectories allows us to quantify the novel skyrmion Hall effect .
Finally to obtain efficient spin transport, we study graphene and low damping ferro- and antiferromagnetic insulators as spin conduits. We find very long distance spin transport in the diffusive regime  and study coherent superfluid transport  that can be controlled in a magnon transistor .
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