Difference between domain wall motion in single crystal and polycrystalline YIG observed by pulsed NMR

Domain wall motion of mono- and polycrystalline YIG were investigated by pulsed NMR (spin echo) technique. The magnitude of the NMR signal for 57Fe in YIG in zero external magnetic field is enhanced by domain walls provided the NMR frequency f/sub n/ < f0, whereas f0 is the relaxation frequency of the wall. It might therefore be expected that the bulging motion of domain walls in a polycrystalline material would lead to a different NMR signal from that in a single crystal where the wall motion would be more nearly planar. The advantage of the NMR technique is that samples can be of any shape