Fig. 2: Experimental BLS images (logarithmic color scale) taken at an applied field of μ0Hx = 50 mT, and ordered according to the frequency of the rf signal supplied by the antenna.
The images are grouped in 3 types. a Low frequency patterns with nodes and antinodes in the x direction and intensity maxima at the bottom left corner of the stripe. b Near \({f}_{{\rm{ac}}}(\vec{k}=\vec{0})\): patterns with tilted energy flow, first approximately in the \(\vec{x}+\vec{y}\) direction, then progressively rotating towards \(\vec{y}\) when increasing the frequency. c High frequency patterns, first exhibiting nodes and antinodes in two directions, then solely in the \(\vec{y}\) direction. The sketches indicates that wavevectors and their group velocities that most contribution to the spatial profile of the BLS signal.
