A method to obtain long lengths of flexible, biaxially oriented substrates with smooth, chemically compatible surfaces for epitaxial growth of high-temperature superconductors is reported. The technique uses well established, industrially scalable, thermomechanical processes to impart a strong biaxial texture to a base metal. This is followed by vapor deposition of epitaxial buffer layers (metal and/or ceramic) to yield chemically compatible surfaces. Epitaxial YBa2Cu3Ox films grown on such substrates have critical current densities exceeding 105 A/cm2 at 77 K in zero field and have field dependencies similar to epitaxial films on single crystal ceramic substrates. Deposited conductors made using this technique offer a potential route for the fabrication of long lengths of high-Jc wire capable of carrying high currents in high magnetic fields and at elevated temperatures.

Recent results on achieving ferromagnetism in transition-metal-doped GaN, AlN and related materials are discussed. The field of semiconductor spintronics seeks to exploit the spin of charge carriers in new generations of transistors, lasers and integrated magnetic sensors. There is strong potential for new classes of ultra-low-power, high speed memory, logic and photonic devices based on spintronics. The utility of such devices depends on the availability of materials with practical magnetic ordering temperatures and most theories predict that the Curie temperature will be a strong function of bandgap. We discuss the current state-of-the-art in producing room temperature ferromagnetism in GaN-based materials, the origins of the magnetism and its potential applications.

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