Researchers spatially vary the strength of superconductivity on a nanometer scale using a ferroelectric material on top.
Building structures in a sheet of superconducting material could lead to new devices for processing information. Researchers now report in Physical Review Letters that the superconductivity of an ultrathin layer can be dramatically suppressed by electrically polarizing an atomically matched layer on top of it. The team was also able to suppress superconductivity in an array of nanometer-sized dots without affecting the material between the dots, raising hopes for new ways to pattern superconducting circuits.
The zero-resistance state of a superconductor appears below a critical temperature T c. Researchers would like to manipulate this transition temperature selectively in circuits, or even suppress superconductivity entirely in some places, to make new kinds of devices. They can weaken the superconductivity and lower Tc by reducing the number of charge carriers (either electrons or positively-charged holes, depending on the material). One way to lower the carrier concentration is to expose a thin layer of the material to an electric field that repels the carriers, pushing them into the external circuit. But with traditional electrodes, this “field effect” is often too small to change Tc very much.
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