Uniaxial Anisotropy in Polycrystalline Garnets

Abstract

In samples of polycrystalline yttrium and lutetium iron garnet which exhibit domain-wall relaxation effects, it is possible to establish uniaxial anisotropy by cooling to low temperature in a magnetic field. This magnetic anneal leads to the development of rectangular hysteresis loops. In lutetium iron garnet,where a particularly strong anneal is found, a uniaxial anisotropy energy of 4500 erg/cc is obtained. After cooling, the easy axis can be shifted in direction by altering the orientation of the applied field; the shift in axis occurs with a finite time constant (order of 15 sec for LuIG).