Control of charge density waves in quantum materials by light and 2D self-assembly

One of the most fascinating states of matter is the charge density wave (CDW) condensate. It has been observed in a diverse range of materials, including 2D transition-metal dichalcogenides (TMDs), cuprate superconductors, and metal-oxides [1]. CDWs are central to the understanding of many correlated electron systems because of their interplay with phenomena like superconductivity, Mott insulating states, and spin-density-waves [1]. In TMDs superconductivity often emerges close to or in concomitance with the CDW with variables such as pressure, chemical doping, or electrostatic gating playing crucial roles. Understanding and controlling CDWs thus gives an inroad to describing their interplay with superconductivity. Understanding the interplay between density waves and the electronic interactions leading to superconductivity in these materials may unveil ways of tuning their transition temperatures, and ultimately lead to new high-temperature superconductors.

This project is based on interdisciplinary experimental studies combining material science, optical spectroscopy and quantum transport experiments.

The PhD will develop in three main areas:

Materials preparation: our laboratory in Bath has established expertise in the growth of TMD single crystals of high quality and their exfoliation into thin flakes. The single flakes, sometimes single-layers, will be stacked on top of flakes from complementary materials in a setup built at Bath for the preparation of heterojunctions. This will be performed in a nitrogen glove-box, thus ensuring high-quality interfaces.

ARPES and optical spectroscopy experiments: the TMDs will be characterized both as single materials and within heterojunctions. These advanced methods are based on angle-resolved-photoemission-spectroscopy (ARPES) as a function of temperature, this will give information on the band structure and the formation of gaps at the Fermi surface. This will be complemented by probes to monitor phonons (Raman) and low energy excitations such as plasmons and the CDW gap by IR spectroscopy or femtosecond reflectivity.

Quantum transport: you will perform carrier transport experiments on stacked flakes at different temperatures and magnetic fields in order to understand the many-body interactions leading to excitonic insulator behaviour or discover new superconducting phenomena.

The project will be supervised by Dr. Enrico Da Como and Prof. Simon Bending at the University of Bath. Laboratories in Bath are part of the Centre for Photonics and Photonic Materials (CPPM) and the Centre for Nanoscience and Nanotechnology (CNAN) offering state of the art facilities. Both supervisors have active collaborations worldwide for research visits and knowledge exchange.

Candidate -

We are looking for motivated applicants with a background in Physics, Electrical Engineering or Physical Chemistry. You should hold, or expect to receive, a First Class or good Upper Second Class Honours degree, or the equivalent from an overseas university. A master’s level qualification would also be advantageous.

Applications -

Informal enquiries are welcomed and should be directed to Dr Enrico Da Como, [Email Address Removed].

Formal applications should be made via the University of Bath’s online application form for a PhD in Physics:
https://samis.bath.ac.uk/urd/sits.urd/run/siw_ipp_lgn.login?process=siw_ipp_app&code1=RDUPH-FP01&code2=0013

More information about applying for a PhD at Bath may be found here:
http://www.bath.ac.uk/guides/how-to-apply-for-doctoral-study/

Anticipated start date: 30 September 2019.