Bubble dynamics and growth-induced anisotropy in (Y,Eu,Tm)3(Ga,Fe)5O12

The wall dynamics in two samples of a garnet with the composition Y1.7Eu0.65Tm0.65Ga0.7Fe4.3O12 are compared. Both samples have an easy axis normal to the plane of the material, but in one case the sample is an epitaxial film and is magnetically isotropic in the plane, and in the other case it is a thin platelet cut from a bulk sample and has in-plane anisotropy. The dynamic behavior as measured by the bubble-collapse technique is significantly different in the two samples. The sample with the in-plane anisotropy has an approximately linear velocity reponse to ∼6000 cm/sec corresponding to a drive field of 60 Oe, whereas the isotropic sample saturates at a velocity of ∼650 cm/sec for a drive field of about 20 Oe. However, both samples have nearly the same dynamic behavior as measured by the bubble-transport technique. The results are compared with the existing theories. In addition, the A and B parameters describing growth-induced anisotropy for this composition are determined