Publications (3)0 Total impact
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J. -C. Rojas-Sánchez,
M. Cubukcu,
A. Jain,
C. Vergnaud,
C. Portemont,
C. Ducruet,
A. Barski,
A. Marty, L. Vila,
J. -P. Attané,
E. Augendre,
G. Desfonds,
S. Gambarelli,
H. Jaffrès,
J. -M. George,
M. Jamet
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ABSTRACT: We have measured the inverse spin Hall effect (ISHE) in \textit{n}-Ge at room
temperature. The spin current in germanium was generated by spin pumping from a
CoFeB/MgO magnetic tunnel junction in order to prevent the impedance mismatch
issue. A clear electromotive force was measured in Ge at the ferromagnetic
resonance of CoFeB. The same study was then carried out on several test
samples, in particular we have investigated the influence of the MgO tunnel
barrier and sample annealing on the ISHE signal. First, the reference CoFeB/MgO
bilayer grown on SiO$_{2}$ exhibits a clear electromotive force due to
anisotropic magnetoresistance and anomalous Hall effect which is dominated by
an asymmetric contribution with respect to the resonance field. We also found
that the MgO tunnel barrier is essential to observe ISHE in Ge and that sample
annealing systematically lead to an increase of the signal. We propose a
theoretical model based on the presence of localized states at the interface
between the MgO tunnel barrier and Ge to account for these observations.
Finally, all of our results are fully consistent with the observation of ISHE
in heavily doped $n$-Ge and we could estimate the spin Hall angle at room
temperature to be $\approx$0.001.
05/2013;
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A. Jain,
C. Vergnaud,
J. Peiro,
J. C. Le Breton,
E. Prestat,
L. Louahadj,
C. Portemont,
C. Ducruet,
V. Baltz,
A. Marty,
A. Barski,
P. Bayle-Guillemaud, L. Vila,
J. -P. Attané,
E. Augendre,
H. Jaffrès,
J. -M. George,
M. Jamet
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ABSTRACT: In this letter, we first show electrical spin injection in the germanium
conduction band at room temperature and modulate the spin signal by applying a
gate voltage to the channel. The corresponding signal modulation agrees well
with the predictions of spin diffusion models. Then by setting a temperature
gradient between germanium and the ferromagnet, we create a thermal spin
accumulation in germanium without any tunnel charge current. We show that
temperature gradients yield larger spin accumulations than pure electrical spin
injection but, due to competing microscopic effects, the thermal spin
accumulation in germanium remains surprisingly almost unchanged under the
application of a gate voltage to the channel.
04/2012;
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A. Jain,
J. -C. Rojas-Sanchez,
M. Cubukcu,
J. Peiro,
J. C. Le Breton,
E. Prestat,
C. Vergnaud,
L. Louahadj,
C. Portemont,
C. Ducruet, [......],
A. Barski,
P. Bayle-Guillemaud, L. Vila,
J. -P. Attané,
E. Augendre,
G. Desfonds,
S. Gambarelli,
H. Jaffrès,
J. -M. George,
M. Jamet
[show abstract]
[hide abstract]
ABSTRACT: Electrical spin injection into semiconductors paves the way for exploring new
phenomena in the area of spin physics and new generations of spintronic
devices. However the exact role of interface states in spin injection mechanism
from a magnetic tunnel junction into a semiconductor is still under debate. In
this letter, we demonstrate a clear transition from spin accumulation into
interface states to spin injection in the conduction band of $n$-Ge. We observe
spin signal amplification at low temperature due to spin accumulation into
interface states followed by a clear transition towards spin injection in the
conduction band from 200 K up to room temperature. In this regime, the spin
signal is reduced down to a value compatible with spin diffusion model. More
interestingly, we demonstrate in this regime a significant modulation of the
spin signal by spin pumping generated by ferromagnetic resonance and also by
applying a back-gate voltage which are clear manifestations of spin current and
accumulation in the germanium conduction band.
03/2012;
