Correlating and controlling surface structure and electronic structure in ruthenate oxides

Supervisors: Profs Phil King and Peter Wahl (St Andrews), Dr Hadeel Hussain and Prof Chris Nicklin (Diamond Light Source)

The physical properties of strongly correlated electron materials exhibit an astonishing sensitivity to tiny changes in their crystal structure, intimately linked to the entangled nature of their electronic states. This PhD project will investigate the surfaces of ruthenate perovskites as an ideal testbed to establish the underlying structure-property relationships and to achieve quantitative understanding of the impact of tiny structural distortions on the exotic quantum many-body states and phases that these systems host, and via this, to establish tuneable and deterministic control. Candidate materials systems including single and multi-layer variants of the Sr-Ru-O and Ca-Ru-O family, including the potential to study heterostructure samples. The project will involve utilizing a combination of state-of-the-art synchrotron methods at Diamond for probing surface structure (surface x-ray diffraction, x-ray standing waves, photoelectron diffraction), with advanced spectroscopic studies at St Andrews (low-temperature scanning tunneling microscopy and spectroscopy, laser-based angle-resolved photoemission). This will allow correlating structural and electronic properties, and developing a coherent understanding of the exotic surface phases of these compounds, which include quantum critical, charge-ordered, Mott, and spin-orbit coupled states. Applicants should have a good understanding of condensed matter physics, and be motivated to explore new research questions and directions. The project will combine experimental measurements, technical developments, and advanced data analysis. The student will also join the Centre for Doctoral Training in Quantum Materials at the University of St Andrews ( ) and will be part of its Centre for Designer Quantum Materials ( ), as well as becoming an active member of the Structures and Surfaces Group at Diamond ( ).