The University of Bath is inviting applications for the following PhD project supervised by Dr Adelina Ilie (https://people.bath.ac.uk/ai213/
) in the Department of Physics.
Next-generation information processing and storage technologies will be spin- and valley- (two further degrees of freedom beyond the familiar electronic charge) based; hence creating device structures that can probe and manipulate these degrees of freedom is an area of extensive investment both academically and industrially.
Vertically-integrated heterostructures, where layers of various materials alternate, are a familiar design in magnetic and spin-related applications, and atomic control over the layers’ thicknesses is required for good control of the resulting effects. For this reason, van der Waals, graphene-like layers of two-dimensional (2D) materials, atom-thin by their nature, are ideal for creating new spin-based structures, such as spin-valves, which are generic building-blocks for a plethora of spin-based devices. Furthermore, completely new quantum systems could be created, for example a topological insulator (i.e. a material that is insulating in the bulk but conductive on the surface) that is also ferromagnetic: i.e. a system where there is spin-momentum locking and protection against backscattering, as well as a dominant spin population.
In this project we propose to create and investigate van der Waals heterostructures between 2D materials, where one of the components is a 2D ferromagnetic insulator. (i) In one configuration, the 2D ferromagnetic insulator is topped by a material with giant spin-orbit splitting. The latter is not spin-polarised in isolation (due to valley degeneracy), but in a heterostructure with a ferromagnetic layer, due to a proximity effect, it becomes spin polarized. (ii) In a second configuration, the ferromagnetic insulator is combined with a topological insulator (TI) that would lead to proximity-induced ferromagnetism in the TI. In both cases, (i) and (ii), the angle of rotation between the two layers in the heterostructure is expected to exert a further degree of control on their coupling and, hence, magnitude of effects.
Experimentally, we will use scanning tunnelling microscopy (STM) and Angle-Resolved Photoemission Spectroscopy (ARPES) at cryogenic temperatures to reveal the relationship between the electronic structure and the angular rotation of the layers; next, spin-polarised (SP-) STM will mimic an atomic-scale spin valve which can reveal the spin-injection between the van der Waals layers, as well as test for proximity-induced ferromagnetism (and its vertical extent) in the topological insulator. Finally, we will create real spin-valves, where another ferromagnetic 2D layer will replace the spin-polarised tip; and test such sandwich devices in an externally-applied magnetic field.
The project affords an excellent opportunity for training at the interface between quantum technologies, condensed matter physics, and nanomaterials, and involves direct experience within the topical field of 2D materials, which is the most active field in solid state physics currently. It will also employ state-of-the-art scanning probe microscopy which will access information at the atomic scale, and a range of device nanofabrication and analysis techniques (e.g. magneto-transport). The project will be supervised by Dr. Adelina ILIE (Lead supervisor) and Prof. Alain Nogaret from the Physics Department. Dr. Ilie has extensive experience with atomic-scale investigations of low dimensional systems (including a wide range of 2D materials, and their heterostructures) using scanning probe microscopy-based techniques, while Prof. Nogaret has a background in nanomagnetic and spin-related devices.
Applicants 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.
Enquiries and applications:
Informal enquiries are welcomed and should be directed to Dr Adelina Ilie on email address [email protected]
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=0014
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: 28 September 2020.