Electronic and nuclear magnetic anisotropy of cobalt-doped ZnO single-crystalline microwires

Using electron paramagnetic resonance (EPR), we investigate the electronic and nuclear magnetic properties of ZnO:Co single crystals, grown by the optical furnace method. The high crystal quality of the studied samples allows for the determination of the full hyperfine and g tensors. We explain how the local magnetic anisotropy of the Co2+ impurities is used as a very fine probe for the local symmetry and crystal quality of the host. The temperature- and power-study of EPR intensities recorded in three static- and microwave-field configurations give a qualitative insight into the dynamics of spin-lattice and spin-spin relaxations. In addition, in the context of nanostructures, we explain how a detailed analysis of the intensities anisotropy can reveal the proportion of ordered and disordered phases.