Magnetism of Dilute Oxides
This chapter discusses the established view of magnetism in the oxides, before reviewing data on a selection of the most widely studied materials and considers the physical models that have been advanced to explain the magnetism, and raise issues. There is much evidence that the magnetism is somehow associated with defects related to the oxygen stoichiometry. Narrow process windows have been delimited where the magnetism can be observed, which differ depending on the deposition method—pulsed-laser deposition, sputtering, evaporation, organometallic chemical vapor deposition, and others. A common feature of the ferromagnetism in Zinc oxide and the other oxides is its tendency to decay over times of order of a few months. The magnetism of dilute and undoped magnetic oxides remains one of the most puzzling and potentially important open questions in magnetism. A new picture of high-temperature defect-related magnetism in oxides is emerging, where there are some contending explanations, based on quite different physical premises.