INVESTIGATIONS OF RELAXATION PROCESSES IN YIG WITH PROPAGATING MAGNETOSTATIC SPIN WAVES

A new method to obtain relaxation times in YIG has been developed by measuring the attenuation and time delay of propagating magnetostatic spin waves. If the dimensions of the sample are properly chosen, a range of applied magnetic field will exist over which the attenuation will increase linearly with time delay. The experimental measurements were performed at room temperature for frequencies between 2 and 4 GHz. The relaxation data expressed in terms of an effective linewidth ΔH, can be fit by the expression ΔH=0.043+0.026f, where ΔH is in oersteds and f is the frequency in GHz. The term linear in the frequency is in good agreement with the result obtained by LeCraw and Spencer using the parallel-pumping method and can be explained by the Kasuya-LeCraw mechanism. A similar process is proposed to explain the constant term except that now the magnon confluence is with a low-energy phonon rather than an optical phonon. This process is allowed since the propagating spin waves are essentially at the bottom of the spinwave manifold. © 1969 The American Institute of Physics.