We demonstrate that focused Ga+ ion irradiation can comprehensively modify the ferromagnetic properties of Ni80Fe20 thin films. Magneto-optic Kerr effect measurements at room temperature and magnetoresistance measurements at temperatures between 1.5 and 270 K characterized the irradiation effects. Irradiation steadily reduced the films’ room temperature coercivity, and a dose of 1.0×1016 ions/cm2 at 30 keV was found sufficient to cause a loss of ferromagnetism at room temperature in films of thickness up to 15.5 nm. In situ end-point detection and postirradiation atomic force microscopy confirmed that the sputtering which accompanied doses up to 1.0×1016 ions/cm2 did not compromise the protective caps on these Ni80Fe20 films. We therefore conclude that the modification of ferromagnetic properties occurred primarily because of direct Ga+ ion implantation. From these results, we speculate that focused Ga+ ion irradiation could be a convenient tool for the nanoscale patterning of magnetic properties in 3d transition metal thin films.

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We have performed transport measurements on bridges patterned in misaligned thin films of the superconductor Tl2Ba2CaCu2O8. There is a c-axis component of current flow along the bridge, giving rise to hysteretic Josephson-like current–voltage curves. The temperature dependence of the critical current follows the Ambegaokar–Baratoff theory with IcRN up to 26 mV at 4.2 K. Microwave emission from the Josephson junctions near Tc (≈103 K) has been detected using an X-band detector. We show that 700±15 junctions in the bridge are actively oscillating, confirming that the junctions are “intrinsic” junctions formed by adjacent copper oxide planes in the Tl2Ba2CaCu2O8 crystal structure.

Using a focused ion beam, we have produced superconductor-normal metal-superconductor junctions by controllably removing a portion of the top layer of a patterned superconductor-normal metal thin film. The high-quality junctions showed Josephson coupling which scaled qualitatively with barrier properties and temperature as expected. The largest product of a junction’s critical current and the normal state resistance measured is 98 μV at 4.2 K. The method has good reproducibility and could be exploited in a number of superconducting electronics applications.

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