PhD fellowship - Superconductivity in Twisted Bilayer of Graphene

PhD fellowship on Superconductivity in Twisted Bilayer of Graphene

A fellowship for an experimental PhD thesis work is now available in the Nano- and Quantum Electronics group at the Department of Physics of the University of Basel: . www.nanoelectronics.ch The advertised position is motivated by one of the most remarkable recent findings, namely that a twisted bilayer at the "magic angle" of 1.2° turns from a semimetal into a superconductor (Cao, Y. et al. Nature 556, 43-50 (2018)). Our group has contributed to graphene research since 2011, with major contributions on ultraclean suspended graphene and - since recent- also on encapsulated graphene and other van der Waals materials such as NbSe2 and WTe2. The former is a well-known superconductor, while the latter is a Dirac/Weyl semimetal or in case of a monolayer a topological insulator.

The phenomenal transition of twisted bilayer into a superconducting state is believed to be due to so-called "flat bands", which arise in superlattices, for example, in twisted bilayer. Instead of having a linear "Dirac spectrum", like in monolayer graphene, the electronic bands assume a small curvature, and hence a large mass due to hybridization of the Dirac cones of the two layers. This seem to increase the superconducting coupling strength. In our own research, we have studied superlattices in aligned h-BN encapsulated graphene and found van-Hove singularities in transport studies with superconducting contacts. These are also places where the bands become rather flat.

Your position

In this thesis, the successful PhD applicant will first concentrate on twisted bilayer graphene and study superconducting properties using electron transport measurements at cryogenic temperature down to the milli-Kelvin regime. Josephson junctions shall be fabricated and used in RF and DC-SQUID geometries to measure the critical current, the current-phase relation and emission and absorption properties. This work is done in team of ~6 persons and in collaboration with partners from Nano-CNR Pisa and NBI Copenhagen.

Your profile

We look for a highly motivated student (preferably a physicist) who is keen to explore fundamental aspects of quantum devices. You should have a dedication for experimental work in the field of quantum science and technology and be ready to collaborate and share your knowledge and experience in a team. We expect a strong dedication and commitment to push the frontiers of experimental physics. Requirement: you need to have a profound understanding of quantum and solid state physics as it is taught in a physics curriculum.

We offer you

We offer state-of-the art infrastructure, a maximum of 4 years funding at a standard PhD salary level, excellent support and supervision and a highly motivated team.