Determining the spin wave exchange constant of ferromagnets using canted high-order exchange magnons

We propose an alternative method for obtaining the spin wave exchange constant of a ferromagnetic material. This involves generating and detecting canted high-order magnons in Co films using a time-resolved magneto-optical Kerr effect instrument, which enables the extraction of the spin wave exchange constant in a single film thickness in a reliable manner. To enhance the sensitivity of high-order magnon detection, we perform simultaneous measurements of differential Kerr rotation and ellipticity on both sides of the film. This method will be particularly useful in practical situations where the magnetic properties of a material vary with thickness or where it is not feasible to produce films of the same quality.