Electrical Detection of Direct and Alternating Spin Current Injected

Electrical Detection of Direct and Alternating Spin Current
Injected from a Ferromagnetic Insulator into a Ferromagnetic Metal
Lihui Bai, P. Hyde, D.M.J. Kumar, B.W. Southern, S. Y. Huang, B. F. Miao, C. L. Chien and C.-M. Hu
Department of Physics and Astronomy, University of Manitoba and Department of Physics and Astronomy, Johns Hopkins University
Spin dynamical coupling
x
1. Spin current emitted
by FMR as an additional
damping reduces
FMR amplitude.
2 µV
o
θ=9
VSP
θ=9
0.2
0.2 µV
o
θ = 12
0.3
0.4
0.5
YIG
Py
θ = 15.6
0.2
0.3
Features:
1 Both amplitudes are enhanced
while both FMR ON
.
2 The line width
of YIG is
broaden than that of Py.
1.0
VSR
PyFMR
0.0
1.0
VSP
YIGFMR
YIGWR
0.5
8
Cross-talking
z
0.0
3. Demonstration of ac spin current plays as a spin torque.
V
-1.0
References
x
Faraday inductive currents
y
1.
2.
3.
4.
5.
6.
0.5
z
H
0.0
iSHE
V
-0.5
-1.4
Both induces ac charge currents
mixing with
the ac charge current due to ac spin current.
20
2. Detection of dc and ac spin current pumped by FMR
in YIG via iSHE and spin dynamical coupling with Py.
1.0
Challenges
12
16
θ (degree)
1. First dual ac spin current pumped experiment
on a NEW FM/FI system (Py/YIG bilayer).
H
dc and ac charge currents
0.6
0.5
0.0
Detection FMRs from each layer separately
y
0.5
V
Magnetization precession (FMR)
Spin Hall eﬀect
0.4
µ0H (T)
Conclusions
dc and ac spin currents
θ = 12
o
0.6
Ac spin torque calculation
(solid lines)
Ferromagnetic metal (Py)
-----------------------------------Ferromagnetic insulator (YIG)
x
o
o
µ0H (T)
Permalloy (Py)
yttrium iron garnet (YIG)
Spin pumping
FMRYIG
H
V
θ = 15.6
Ferromagnetic metal/Ferromagnetic insulator
Detection via iSHE
y
o
Ac spin current
Spin current Ac spin current
FMRPy
z
V
3. The second FMR
compensates the spin
current leading to FMR
amplitudes enhancement.
Spin polarized
charge current
z
y
2. Spin current acts on a
magnetization as spin
torque exciting precession.
charge current
x
H
Normalized Amplitude
1 Switches magnetization to write information in memory device.
2 Drive magnetization precession to generate microwave.
3 Drives magnetization precession as spin wave emitter.
Ac spin current as ac spin torque
VSR
Spin current and its applications
-0.7
0.0
0.7
1.4
FMR in Py is dected as spin rectiﬁcation by setting H ﬁeld in x-z plane
FMR in YIG is detected as spin pumping by setting H ﬁeld in y-z plane
Luqiao Liu, et. al. SCIENCE 336, 555 (2012).
N. Locatelli, et. al. Nature Materials 13, 11 (2014).
Y. Kajiwara, et. al. Nature 464, 262 (2010).
M. Johnson, R. H. Silsbee, Phys. Rev. Lett. 55, 1790 (1985).
H.J. Jiao and G. E. W. Bauer, Phys. Rev. Lett. 110, 217602 (2013).
P. Hyde, Lihui Bai, D.M.J. Kumar, B. Southern, S. Y. Huang, B. F. Miao,
C. L. Chien, and C.-M. Hu, Arxiv: 1310.4840. Accepted by Phys. Rev. B
Lihui Bai Email: [email protected]

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