[Todos] Coloquio Extraordinario, Departamento de Física, miercoles 13/7, 14hs
pdmitruk en df.uba.ar
pdmitruk en df.uba.ar
Jue Jul 7 15:21:34 ART 2011
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COLOQUIO EXTRAORDINARIO
DEPARTAMENTO DE FÍSICA FCEyN - UBA
http://coloquios.df.uba.ar/
Charla, café y galletitas
En el Aula Federman, 1er piso, Pabellón I,
Ciudad Universitaria
Miercoles 13 de julio, 14hs,
Pure Spin Currents: Discharging Spintronics
Axel Hoffmann
Materials Science Division
Argonne National Laboratory
Illinois, USA
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. Mihajlovi , 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).
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