In an electron fluid, both resistive and viscous mechanisms can be present. In systems with perfect translational invariance momentum is a conserved quantity, and as the electrons carry both charge and momentum, the current cannot decay. Predictions from theories at the particle physics-condensed matter physics interface using the `AdS/CFT' correspondence suggest that hydrodynamic charge flow might exist in some exotic metallic states. In the high-Tc cuprates the T-linear resistivity in the strange metal regime is conjectured to be due to hydrodynamic effects.
In this dissertation, I start out drawing a theoretical outline of the hydrodynamic theory of electron transport in solids. In the search for a high purity metal that can host such a hydrodynamic electron transport, we looked at the non-magnetic delafossite oxides PdCoO2 and PtCoO2, which have the highest conductivities of any known oxides, and whose key properties I will review. As the signatures of viscosity can only be realised in transport through boundary scattering, the samples had to be taken down to the mesoscopic limit, where the momentum conserving and relaxing scattering mean free paths of the material are comparable to the channel width. I will discuss the focussed ion beam (FIB) micro-structuring technique that I have implemented to fabricate the mesoscopic devices.
To interpret the transport in the mesoscopic regime, a comprehensive understanding of the bulk transport is first necessary and I will present my measurements of the magnetoresistance and Hall effect in both materials, which show deviations from the predictions of standard models highlighting some intriguing physics even in the bulk limit.
Finally, I will present the data from magnetotransport measurements at the mesoscopic limit. Magnetic field introduces a variable length scale, the cyclotron radius, in the system which can be used to tune through different transport regimes. I will discuss the ballistic and hydrodynamic signatures in the transport that becomes accessible through magnetic field tuning in the mesoscopic samples of the delafossites PdCoO2 and PdCoO2.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:34882 |
| Date | 09 August 2019 |
| Creators | Nandi, Nabhanila |
| Contributors | Klauß, Hans-Henning, Mackenzie, Andy, Schmalian, Jörg, Technische Universität Dresden, Max-Planck-Institut für Chemische Physik fester Stoffe |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
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