Microwave Absorption in High T sub c Single Crystals

Microwave absorption is proving to be a sensitive technique for the characterization of high T sub c materials. Magnetic losses result from the failure of induced currents to follow applied fields. With polycrystalline materials, losses are observed at all temperatures below T sub c , whereas in single crystals they are often restricted to a narrow range just below T sub c . We shall examine the temperature, field, and angular dependence of loss measurements on single crystals and their possible interpretations.