Thanks to the continuous development of material science, various novel nanostructures from two dimensional van der Waals crystals to semiconductor nanowires or advanced semiconductor/superconductor heterostructres to exotic topological structures exist, which are promising platform to engineer novel devices for quantum electronic or spintronic applications. Gating effect is the standard way to control and tune the properties of such nanodevices, which can change the charge carrier density, modify tunnel barriers etc. In this phd program we plan to use novel direction to modify electric property of nanodevices, where the influence of applied pressure is studied. Based on theoretical predictions interesting results are expected e.g. for van der Waals heterostructures: The interplay between subsequent layers is defined by the tunnel coupling, which is exponentially sensitive to distance and thereby to pressure. Thus strong change in proximity effects, or modification of quantum phase transitions are expected.
Combination of hydrostatic pressure cell with the special requirements of a nano chip is challenging. However our first tests with a prototype piston based pressure cell setup demonstrate the feasibility of transport measurements on nanochips under pressure.
In a pressure cell, the nanochip is in a pressure transmitting medium, for which ionic liquids can also be used. Ionic liquids allows order of magnitude larger gating effect than conventional gating with electrodes, thus nanodevices could be studied at unusual electron densities. E.g. non-conducting, semiconductor TMDC layers could be driven to (super)conducting state.
The task for the applicant is to further develop the prototype pressure cell system and carry out low temperature transport characterization of various nanodevices. The work is done in close collaboration with several European universities.
Knowledge of solid state physics, motivation and experience with experimental work, English knowledge, basic programming and measurement automation experience.