CAREER: Spin-Resolved Imaging of Correlated Electron Systems Including Cuprates and Pnictides

Harvard University, Cambridge MA

Investigators

Abstract

NON-TECHNICAL ABSTRACT This CAREER award funds a project to image electron spins in complex materials. Although electrons in metals mind their own business, barely interacting with each other, in so-called 'strongly correlated electron' materials the interactions of electrons drive unique properties that are fascinating and often useful. For example, so-called high-Tc superconductors carry electricity without loss at economically feasible temperatures; multi-ferroic materials allow electronic data storage using a magnetic field and magnetic data storage using an electric field; heavy fermion materials boast electrons behaving with thousands of times their actual mass; simple sheets of carbon called graphene allow electrons to zip along as if they had no mass at all. These materials have in common that their electrons interact strongly, and that those interactions are poorly understood. This project will employ a spin-polarized scanning tunneling microscope to measure the energies and locations of electron spins with atomic resolution, starting with superconductors. The project will also use this technology to educate three deserving groups: Harvard students will benefit from a new undergraduate course on scanning tunneling microscopy; local elementary school children will be invited to see a working science lab viewing real electrons; interested citizens will be able to browse a colorful website explaining the fascinating variety of materials under investigation. TECHNICAL ABSTRACT This CAREER award funds a project to image electron spins in high-Tc superconductors, both cuprates and pnictides. The common feature to these exotic materials is that their electrons interact strongly, and there is no broadly successful theoretical language to describe these so-called 'correlated electron materials'. Great strides have been made through various methods of imaging the interactions of electron charges, but understanding has been limited by the lack of effective tools to image the interactions of electron spins. This project will employ a low temperature spin-polarized scanning tunneling microscope to measure the spin-resolved density of electronic states with atomic resolution. In particular, a comparison will be made between spin interactions in cuprates and pnictides, the only two known families of high-Tc superconductors, discovered in 1986 and 2008. The project will also use this spin imaging technology to educate three deserving groups: Harvard students will benefit from a new undergraduate course on scanning tunneling microscopy; local elementary school children will be invited to see a working science lab imaging real electrons; interested citizens will be able to browse a colorful website explaining the fascinating variety of strongly correlated materials under investigation.