Optical detection of ferromagnetic resonance in K₂CuF₄

Abstract

Ferromagnetic resonance (FMR) was investigated in K2CuF4 by observing scattering of light from the crystal under microwave excitation at frequencies around 35 GHz. The spectrum of the scattered light contains satellites whose frequency differs from that of the incident light by the amount of the FMR frequency. The intensity of the satellites is used to estimate the number of the uniform precession magnons and to study their relaxation in a wide range of pumping powers. The power dependencies of the different magnetostatic modes are separately measured and show marked non-linearities. Investigations with light propagating along the c and a axes of the crystal are used to obtain information on the spin wave energy gap.