A strong mutual influence of superconductors (S) and ferromagnetic (F) conductors in hybrid F͞S (Ni͞Al) nanostructures is observed. The proximity-induced conductance on the F side, DG, is 2 orders of magnitude larger than that predicted by theory. A crossover from positive to negative DG takes place upon an increase in the F͞S interface barrier resistance. Reentrance of the superconductors to the normal state reciprocated by changes on the F side has been found in low applied magnetic fields with new peaks in the differential resistance as an effect of the saturation magnetization. An analysis has been developed providing a base for a numerical description of the system.

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We observe large amplitude changes in the resistance of ferromagnetic (F ) wires at the onset of superconductivity of adjacent superconductors (S). New sharp peaks of large amplitude are found in the magnetoresistance of the F -wires. We discuss a new mechanism for the long-range superconducting proximity effect in F/S nanostructures based on the analysis of the topologies of actual Fermi-surfaces in ferromagnetic metals.

The Power Chips technology employs a gap of 4-10 nanometers in a gap diode to allow for efficient thermal conversion with very low thermal leakage. The design ∆T is on the order of 400 degrees single stage, with operation possible from 1 K to 1600 K, depending on configuration and meeting engineering challenges. Efficiency is projected to be in the range of 70% of Carnot-defined maximum. R&D work on this approach has been in progress since 1997. The main technical challenge of fabricating and maintaining the required gap has been overcome; thin film and packaging issues remain. The technology is anticipated to be ideal in terms of size, weight, efficiency, and reliability. Power Chips can be packaged identically as conventional thermoelectrics making them a drop-in replacement in many cases including RTGs. Applications for Power Chips include RTGs as well as thermal conversion from a waste heat stream or solar-thermal conversion.