All in situ/ultra-high vacuum ionic liquid gating study

Electrostatic gating is a common approach to tune the properties of materials. It is utilized in field effect transistors in which the carrier concentration can be reversibly controlled by applied electric fields. Recently it has been found that by replacing the conventional solid-state gates with ionic liquids (ILs), much higher electric fields can be implemented. Consequently, much higher charge carrier densities, and thus exciting phase transitions can be induced.

A purely electrostatic charge accumulation has been assumed to cause the IL gating effects. However, many recent studies show that the experimental observations are not in agreement with a purely electrostatic picture, but rather related to electrochemical processes. The exact mechanisms are still being discussed. One reason underlying these controversies might be a lack of purity in the experiments. Most ILs are known to be very hygroscopic. They easily absorb water from the atmosphere which can considerably change their properties. Thus, a careful handling of the ILs is required.

The Department Physics of Correlated Matter at the Max Planck Institute for Chemical Physics of Solids, Dresden, has a great expertise in the growth (molecular beam epitaxy (MBE)) and characterization of high-quality thin films all under ultra-high vacuum (UHV) conditions. The goal of this PhD project is to perform IL gating studies entirely under ultra-high vacuum including sample and IL device preparation, gating, and characterization. We are looking for a student with background in solid state physics and hands-on lab experience, who is also interested in building and optimizing experimental setups.

Ultra-high vacuum system for the preparation and characterization of oxide and topological insulator thin films including ionic liquid gating facility.

Publications

D. Passarello, S. G. Altendorf, J. Jeong, C. Rettner, N. Arellano, T. Topuria, M. G. Samant, and S. S. P. Parkin
Evidence for Ionic Liquid Gate-Induced Metallization of Vanadium Dioxide Bars over Micron Length Scales
Nano Letters 17 (5), 2796 (2017)
C. ViolBarbosa, J. Karel, J. Kiss, O.-d. Gordan, S. G. Altendorf, Y. Utsumi, M. G. Samant, Y.-H. Wu, K.-D. Tsuei, C. Felser, and S. S. P. Parkin
Transparent conducting oxide induced by liquid electrolyte gating
Proceedings of the National Academy of Sciences of the United States of America 113, 11148 (2016)
D. Passarello, S. G. Altendorf, J. Jeong, M. G. Samant, and S. S. P. Parkin
Metallization of Epitaxial VO2 Films by Ionic Liquid Gating through Initially Insulating TiO2 Layers
Nano Letters 16, 5475 (2016)
S. G. Altendorf, J. Jeong, D. Passarello, N. B. Aetukuri, M. G. Samant, and S. S. P. Parkin
Facet-Independent Electric-Field-Induced Volume Metallization of Tungsten Trioxide Films
Advanced Materials 28, 5284 (2016)

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