Vacancies

Vacancies:

Imaging Multifunctional Nanomaterials in Three-Dimensions with Coherent X-rays

Multifunctional materials that simultaneously exhibit more than one ferroic property including ferromagnetism, ferroelectricity, ferroelasticity or ferrotoroidicity are of great interest because the different properties may work together in different ways and lead to exciting new potential applications, if we could understand this better. For example, the coupling between magnetic and ferroelectric ordering can be utilised to develop low power magnetoelectronic devices (such as non- volatile magnetic computer memory) where the spin polarised transport of electrons can be used to flip magnetic memory bits. As a result there is a vibrant effort to understand the underlying mechanisms at work in bulk and thin film materials. Often the role of crystal defects and other topological structures remains unclear as (to date) no reliable means exists to image in three-dimensions and observe such effects in real-time. In addition, common Li-ion battery cathode materials such as Li_xCoO₂ (LCO) allow high capacities and reliable cyclability, but suffer from structural degradation over repeated charging cycles.

The aim of this project is to image time-varying correlated phenomena in a range of multifunctional materials. The results will (1) facilitate in identifying new and potentially novel applications for the materials of interest, (2) provide insight into scale-invariant properties of correlated material systems and (3) provide improved performance of battery materials.

To better understand these materials we will use a technique called Bragg coherent X-ray diffractive imaging (BCXDI) without lenses to reveal how novel phases emerge and influence the material properties. The application of BCXDI to the study of multifunctional materials will enable a wide range of next generation technologies that otherwise are inaccessible due to an incomplete understanding of their properties. The successful candidate will spend approximately 50% of their time on the project working at the Diamond Light Source, located at the Harwell Science and Innovation Campus in Oxfordshire.

Applications are invited from bright and highly motivated students with a background in physics, materials science, inorganic chemistry or a related field. The successful candidates will have obtained either a First or Upper Second class honours degree.

Ultra-fast X-ray Imaging of Nanoscale Structures

A long standing dream of chemical physics is to directly observe atomic motions during the event of a chemical transition from one state to another. The ability to quantitatively observe atomic motions within the transition state region where atoms exchange nuclear configurations would greatly facilitate our understanding of the physical process. This is particularly true for strongly correlated electronic materials where the interaction between the valence electrons can strongly influence the materials properties. Such materials are interesting as their unique properties are of considerable utility for device physics, functional materials and the study of fundamental condensed matter physics. The aim of this project is to understand the initial stages of the femtosecond structural phase transition in strongly correlated electronic materials such as vanadium dioxide. The candidate will become proficient in the use of femtosecond Bragg coherent X-ray diffraction imaging (BCXDI) for studying femtosecond structural dynamics in nanometre scale self-assembled structures.

To investigate strongly correlated phenomena the student will focus on one or more components to this multidisciplinary project. They include (1) nanoscale materials fabrication and characterisation; (2) time-resolved femto-second Bragg coherent X-ray diffraction imaging (BCXDI); and (3) supercomputing based finite element materials modelling of light matter interactions.

The successful candidate will work with an international team of research scientists with a broad range of skills. The successful candidate will also visit a number of research facilities across the world including the European XFEL facility in Germany, SACLA XFEL facility in Japan and the Diamond Light Source to perform experiments.

Applications are invited from bright and highly motivated students with a background in physics, materials science, inorganic chemistry or a related field. The successful candidates will have obtained either a First or Upper Second class honours degree. International students are required to provide evidence of their proficiency in English language skills.