Surface acoustic waves in dynamic magnonic crystals for microwave signals processing

Surface acoustic waves (SAW) in dynamic magnonic crystals (DMC) are considered for their use to create tunable spin-wave gadgets for processing of microwave signals. To understand the principles of operation of the proposed gadgets, the necessary basic properties of DMC created by a SAW in the structure of "yttrium iron garnet film on a substrate of gallium gadolinium garnet" are given. The prototype of the unique nonreciprocal notch filter working in the range of 3600-4100 MHz at the biasing magnetic field of 640 Oe is fabricated and its main characteristics such as dependences of the frequency and the depth of rejection pits on the frequency and power of the controlling SAW are measured. At the frequency of SAW of 41 MHz and power of 30 mW, the depth of the rejection pit reached 23 dB, the tunable shift of the notch frequency equaled to 7 MHz for a frequency change of SAW by 1 MHz. DMC with SAW may also be used for frequency shifting and modulation of microwave signals. Two configurations of prototypes of frequency shifting devices have been suggested, fabricated and their workability was shown experimentally.