Cobalt content- and magnetic field-dependent transmission behaviors of red laser light for Co Al 2 O 3 granular thin films

Abstract The transmission of red laser light with wavelength λ = 632.8 nm of Co x -(Al 2 O 3 ) 1- x magnetic granular thin films was investigated under the effect of external magnetic field H (0–500 Oe). Results showed the behaviors of variation in the T transmittance ratio as a function of H exhibit three trends depending on the Co content x : (1) T declines to a saturation value called the floor level of the transmission T flo when x T tends to reach a maximum and then decreases to a saturation floor level when x = 0.49; and (3) T increases to a saturation value called the ceiling level of the transmission T cei , when x > 0.49. T flo increases in accordance with x when x T cei decreases rapidly when x approaches 1. These phenomena were considered to be related to the magnon – plasmon interactions from excitation by photons for the spins polarized in the Co particles.