Coexistence or Competition: Resolving the phase diagram in unconventional superconductors at the atomic scale

Many unconventional superconductors such as copper-oxide, iron-based and heavy fermion superconductors exhibit very similar phase diagrams as a function of doping or pressure with structural and magnetic phase transitions in the vicinity of a superconducting dome. Superconductivity in these materials is not mediated by phonon coupling as in conventional superconductors, but rather either by magnetically mediated coupling or due to electronic correlations. In this regard, the importance of the magnetic and structural phases in these materials for superconductivity, and whether they coexist or compete with superconductivity become important questions. In this project, the aim is to image the relation between these two phases at the atomic scale to unravel their relation. The project builds on recent results in the group establishing imaging of magnetic structure by spin-polarized STM for the first time in a strongly correlated electron material which is relevant for unconventional superconductivity.1 You will be using state-of-the-art low temperature scanning tunneling microscopes, which are installed in a new ultra-low-vibration facility at the University of St Andrews.

[1] M. Enayat, Z. Sun, U. R. Singh, R. Aluru, S. Schmaus, A. Yaresko, Y. Liu, C. Lin, V. Tsurkan, A. Loidl, J. Deisenhofer, and P. Wahl, Science 345, 653 (2014).