Electric Double Layer formation in SrTiO3 and Nd2-xCexCuO4

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Electric Double Layer formation in SrTiO3 and Nd2-xCexCuO4

Type: Master thesis
Title: Electric Double Layer formation in SrTiO3 and Nd2-xCexCuO4
Author: Leeuwenhoek, Maarten
Issue Date: 2015
Keywords: Electric double layer
liquid gating
ionic liquids
strontium titanate
cuprates
Abstract: In recent years Electronic Double Layer (EDL) gating using ionic liquids or organic electrolytes has been successful in tuning carrier densities in materials such as ZnO [1], SrTiO3 [2–4], La2-xSrxCuO4 [5] and YBa2Cu3O7- [6]. The potential for studying High-Tc superconductors and Metal-Insulator transition with great flexibility has been shown. The carriers are pulled into a 1nm layer by the accumulation of ions on the surface (EDL). Here the formation the EDL in time is studied on atomically flat SrTiO3 (100) single crystals and electron doped High-Tc superconductor Nd2-xCexCuO4 thin films. At temperatures close to the melting point of the ionic liquid (DEMETFSI) the ability to separate the EDL formation on the contacts from the formation on STO is demonstrated by measuring resistance and gate current as a function of time. This despite the presence of a significant Faradaic current most likely due to oxidation/reduction at the gold surface. It is argued that the EDL formation on the STO originates from the contacts and its growth largely depends on the mobility of the ions. Measurements on (undoped) Nd2CuO4 show a resistance decrease up to 90% at Vg = 3V and thereby showing the potential of EDL gating on electron doped cuprates.
Supervisor: Ruitenbeek, Jan van
Faculty: Faculty of Science
Department: Physics (Master)
Specialisation: Research in experimental physics
ECTS Credits: 5
Handle: http://hdl.handle.net/1887/40572
 

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