IEEE MAGNETICS SOCIETY DISTINGUISHED LECTURE Pure Spin Currents: Discharging Spintronics
CIC nanoGUNE Seminars
- Speaker
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Axel Hoffmann, Argonne National Laboratory, Argonne, USA
- When
-
2011/06/02
14:00 - Place
- nanoGUNE seminar room, Tolosa Hiribidea 76, Donostia - San Sebastian
- Add to calendar
- iCal
As semiconducting electronic devices are miniaturized to ever-smaller
dimensions, power dissipation becomes an ever-increasing problem due to
leakage charge currents. Spintronics may help addressing some of these issues
by utilizing besides the charge degree of freedom also the electron spin.
Conventional spintronics approaches are used for non-volatile devices, such as
magnetic random access memory, where spin currents are mainly considered as
spin-polarized charge currents and as a result the spin and charge currents
are in parallel and directly coupled. Looking further into the future, the
question arises, whether eliminating charge currents altogether could provide
additional benefits for applications. Towards addressing this question, non-
local device geometries allow for separating spin and charge currents, which
in turn enables the investigation and use of pure spin currents [1]. This
approach opens up new opportunities to study spin-dependent physics and gives
rise to novel approaches for generating and controlling angular momentum flow.
In this lecture, I will discuss different approaches for generating pure spin
currents, such as non-local electrical injection from a ferromagnet, charge-
to-spin current conversion via spin Hall effects, and spin pumping from
ferromagnetic resonance. Furthermore, I will show how spin currents can then
be used for gaining new insights into spin dependent phenomena. In
particular, the temperature dependence of spin and charge relaxation times
allows to identify different spin relaxation mechanisms [2]. In addition,
spin pumping facilitates the generation of macroscopically large pure spin
currents. This permits to quantify spin Hall effects with great precision,
even in materials where these effects are relatively weak [3,4]. Finally, I
will conclude with a brief outlook on the current scientific and future
technological opportunities for pure spin currents.
This work was supported by the U.S. Department of Energy, Office of Science,
Basic Energy Sciences, under contract No. DE-AC02-06CH11357
[1] A. Hoffmann, Phys. Stat. Sol. (c) **4** , 4236 (2007).
[2] G. Mihajlović, J. E. Pearson, S. D. Bader, and A. Hoffmann, Phys. Rev.
Lett. **104** , 237202 (2010).
[3] O. Mosendz, J. E. Pearson, F. Y. Fradin, G. E. W. Bauer, S. D. Bader, and
A. Hoffmann, Phys. Rev. Lett. **104** , 046601 (2010).
[4] O. Mosendz, V. Vlaminck, J. E. Pearson, F. Y. Fradin, G. E. W. Bauer, S.
D. Bader, and A. Hoffmann, Phys. Rev. B **82** , 214403 (2010).