Superconductivity and Correlated Electrons
Three-dimensional image of the dynamic resistance of the vortex system in a square proximity array as a function of the driving current (horizontal axis) and the applied magnetic field (axis receding into the distance). The valley corresponds to zero vortex mobility, hence zero resistance, and the spike-like tributary streams at commensurate fields mark vortex Mott states that form when the number of vortices is commensurate with the number of traps. [Science 349, 6253 (2015)]
Complex ordered states arise in materials when electron spin, charge and orbital interactions couple together and with the crystal lattice, resulting in superconductivity, magnetism and intriguing topological and quantum states. Furthermore, strongly driven systems can show signatures of ordered states, such as superconductivity at high temperatures, enabling the development of concepts for new applications that can transmit power with low loss.
The research in this theme investigates the complex phenomena arising from interactions in novel bulk materials, thin films, heterostructures and in quantum nano- and mesoscopic systems. Work in this theme focuses on the role of competing interactions and phase competition in generating novel phenomena, such as unconventional superconductivity and magnetic order in cuprates and iron-based superconductors.
Research in this theme also explores mesoscopic quantum materials where quantum interference and fluctuations, coupled with long-range interactions and disorder, leads to coherence on the meso- and macro-scales to mediate entanglement phenomena. These interactions can lead to intriguing phenomena, such as novel low-temperature super-insulating states in strongly disordered superconducting films and re-entrant superconductivity in nano-patterned superconducting films and strips at high magnetic fields.
As we attempt to connect materials with applications, we identify that vortex behavior in a superconductor controls all the electromagnetic response of high-performance superconductors. Here, this theme focuses on developing novel strategies for controlling vortex dynamics at high temperatures by creating nano-engineered magnetic, adaptive and smart vortex pinscapes to tailor their electromagnetic behavior. Superconductivity and correlated electron research involves leading programs in both experiment and theory, with each deriving strong benefit from close mutual cooperation.