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Spin-conversion effects using spin textures in momentum space

Speaker: 
Hidekazu Kurebayashi (London Centre for Nanotechnology, UCL)
Date: 
Wed, 20/04/2016 - 11:00am to 12:00pm
Location: 
Physics Conference Room (S11-02-07)
Host: 
Goki Eda
Event Type: 
Seminars

Abstract

The spin-orbit interaction has been providing richness and greatness of magnetism and spintronics. In solid states, it couples electron’s momentum and spins, which make it possible to electrically excite or detect spin accumulation/currents. Looking at localized spins, it is the microscopic origin of magnetic anisotropies (together with the magnetic-dipole interaction) where the sample’s real space symmetry, such as surface-induced two-fold and crystalline-induced four-fold, is reflected on the magnetic energy landscape. Along this line, we can also think of what will happen when we lower the sample symmetry to “inversion broken”. In this case, an electron propagating along one direction is, on the symmetry argument, no longer required to be on the same state as ones moving to the opposite direction. The spin-orbit interaction picks up this and causes a preferential spin direction for each electronic state, as a whole, forming spin textures in momentum space. These spin textures are a fascinating playground for developing spin-conversion effects. Although the electric excitation of spin textured materials has been known as the Edelstein effect [1] for more than two decades, its real spintronic use, e.g. magnetisation control [2], has been much more recent interest. In this talk, I will summarise our recent results on spin-conversion effects using GaMnAs spin textures. I will show microscopic origins of current-induced magnetisation control by the Edelstein effects in single ferromagnetic layers [3], as well as by non-magnetic layers [4]. In addition, I will touch upon charge pumping experiments by magnons [5].

[1] Edelstein, Solid State. Comm. 73 233 (1990).
[2] Chernyshov, et al., Nature Phys., 5 656 (2009).
[3] Kurebayashi, et al., Nature Nanotech, 9 211 (2014).
[4] Skinner et al., Nature Comm. 6 6730 (2015).
[5] Ciccarelli et al., Nature Nanotech. 10 50 (2015).

Speaker's details

I have broad interests in spin transport, generation, manipulation and beyond, with a determination to contribute to furthering our scientific understanding and technological abilities. I am at the moment very much fascinated by a diverse range of phenomena arising from the spin-orbit interaction, in particular, that projects the real space (sample) structures and symmetries into spin structures in the (electronic) momentum space. These form a pivotal role in our modern physics and materials science research, often in the nanoscale, that I feel there are much more to explore. Understanding of the spin-orbit natures in condensed matter and resultant rational selections of appropriate materials&structures can potentially push the boundary of what it calls the state-of-the-art in the nanotechnology.

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