190
M. Mochizuki
0.02
0.06
(d)
(e)
=30°
=0°
Rotation
(CCW)
0.1
Rotation
(CW)
0.02
0.06
0.1
Breathing
H ||x
H ||y
H ||z
0
0.1
0.2
Microwave Absorption (arb. units)
Rotation
(CCW)
Rotation
(CW)
Breathing
Rotation mode
(CCW)
H ||x,y
=0.055
-1
1
m iz
Breathing mode
H ||z
=0.062
(a)
t = t0
t = t0 + 3T/4
Rotation mode
(CW)
H ||x,y
=0.092
=30°
=0°
t = t0 + T/4
t = t0 + T/2
(c)
(b)
Fig. 8.3 a–c Simulated snapshots of the three spin-wave modes of a skyrmion crystal confined
in a quasi-two-dimensional thin-plate magnet under a perpendicular H ex field. Here one skyrmion
in the skyrmion crystal is focused on because all the skyrmions oscillate uniformly in each mode.
The two rotation modes with counterclockwise (CCW) and clockwise (CW) rotation senses are
active to an in-plane microwave magnetic field H ω y, whereas the breathing mode is active
to an out-of-plane microwave magnetic field H ω d Calculated microwave absorption spectra
under perpendicular (θ = 0 ◦ ) and tilted (θ = 30 ◦ ) H ex fields as functions of the microwave angular
frequency ω for the in-plane microwave field H ω y. e Those for the out-of-plane microwave field
H ω Here the simulations are performed for J = 1, D/J = 0.27, H z = 0.036, H ω = 0.0018,
and α G = 0.02 (Reproduced from [29].)