Electric field-tuned unconventional superconductivity in nanoelectronic devices

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The quantum critical ferroelectrics SrTiO3 and KTaO3 are usually band insulators but can be transformed into metals by introducing electron charge carriers using ionic-liquid voltage gates. Metallicity can be switched on and off by the simple application of a few volts and IBM have a programme to fabricate vast arrays of SrTiO3-based micro-transistors. Gated SrTiO3 and KTaO3 become superconducting below 1K with a dome of superconductivity in the temperature carrier-density phase diagram. A recent theory has unlocked the mystery of how such materials become superconductors which points to the role of hybrid polar modes in creating electron pairing states. This insight allows us to anticipate superconductivity in a range of new materials. The PhD project builds on the work and skills ascertained in the midi project to identify candidate anti-ferroelectrics that may be doped with electrons and tuned to quantum critical points. Epitaxial thin-film perovskites with varying chemical compositions will be prepared using pulsed-laser deposition. Nanoelectronic devices will be fabricated appropriate for ionic-liquid gating experiments. mK refrigerators will be used to search for unconventional superconductivity, perhaps with enhanced transition temperatures, and to investigate the electrical properties of the novel metallic state and the insulator-metal transition.