I discuss some recent investigations on bulk and nanoparticulate inorganic materials which exemplify the great current interest in the field of spintronics, a spin-based vision of electronics. The emphasis of the work is to demonstrate that the chemistry of inorganic materials has much to contribute to this exciting, emerging area.

Magnetic semiconductors are an essential component in spin rectification, and there is great interest in rendering wide band-gap materials such as ZnO or TiO₂ magnetic through suitable substitution. We have been trying to induce dilute ferrimagnetism in wide band-gap hosts; ZnGa₂O₄:MFe₂O₄ solid solutions are magnetic with strongly hysteretic behaviour at 5 K whilst retaining a relatively large band gap.

The injection of spin requires half-metallic ferromagnets; magnetic systems with electrons in only one spin direction at E_F. We have studied the pyrite system Co_1-xFe_xS₂ using a variety of techniques and attempted to correlate half-metalicity with crystal structure and bonding. Results on other chalcogenide magnets are also presented.

By creating interfaces between different kinds of magnets (eg. ferromagnets and antiferromagnets, or between soft and hard ferromagnets), the magnetic hysteresis loop can be exchange-biased. I discuss the synthesis, structure, and magnetism of core-shell ferrite nanoparticles that reproduce such exchange biasing on the nanometer scale.

Date: Thursday, February 24, 2005
Time: 4:10 pm.