Condensed Matter Seminar: Professor Mathias Kläui, Johannes Gutenberg University
- Date: Tuesday 11 June 2019, 14:00 – 15:00
- Location: EC Stoner SR (9.90) Abstract:
- Type: Seminars, Physics and Astronomy
- Cost: Free
Professor Mathias Kläui, of the Institute of Physics, Johannes Gutenberg University, Mainz, will be presenting a seminar on his research. All are welcome to attend.
Topological Spin Dynamics for GreenIT Abstract: 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 .
 Reviews: O. Boulle et al., Mater. Sci. Eng. R 72, 159 (2011); G. Finocchio et al., J. Phys. D: Appl. Phys. 49, 423001 (2016); K. Everschor-Sitte et al., J. Appl. Phys. 124, 240901 (2018).  Z. Jin et al., Nature Phys. 11, 761 (2015).  F. Büttner et al., Nature Phys. 11, 225 (2015).  S. Woo et al, Nature Mater. 15, 501 (2016).  K. Litzius et al., Nature Phys. 13, 170 (2017).  S. Geprägs et al., Nature Commun. 7, 10452 (2016).  R. Lebrun et al., Nature 561, 222 (2018)  Y. Tserkovnyak and M. Kläui, Phys. Rev. Lett. 119, 187705 (2017)  J. Cramer et al., Nature Commun. 9, 1089 (2018)
Host: Dr Satoshi Sasaki