18
T. Yu and G. E. W. Bauer
Fig. 1.6 Microwave
reflection ReS 11 (a) and
transmission ReS 12 (b)
amplitudes, (1.41), for a
system of two Co nanowires
on a YIG film as a function
of frequency ω in . The
radiative damping of both
nanowires is
κ p /(2π) = 10 MHz and
other parameters are given in
the text
40
60
80
100 120 140 160
B (mT)
7.5
8
8.5
9
9.5
10
10.5
ω
in /(2π) (GHz)
0.97
0.975
0.98
0.985
0.99
0.995
1
(a)
40
60
80
100 120 140 160
B (mT)
7.5
8
8.5
9
9.5
10
10.5
ω
in /(2π) (GHz)
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
(b)
lengths and lifetimes. We focus on the Kittel magnons in the wires since the dipolar
coupling between the film and higher bands in the nanowire is very small. The coupling strength |g k | in Fig. 1.5 illustrates that magnons with wavelength around half
of the nanowire width (here π/w = 0.045 nm
−1 ) dominate the coupling. Pumping
from other than the those modes can therefore be disregarded even at elevated temperatures. Furthermore, the spin current in the film is dominated by spin waves with
small momentum and long mean-free paths, so the effects of magnon-magnon and
magnon-phonon interactions that otherwise render magnon transport phenomena diffuse [21] should be negligibly small. The narrow-band thermal injection requires an
inductive (or optical) detection of the magnons accumulated in the detector contact,
since the inverse spin Hall effect with heavy metal contacts is very inefficient.