Name of project:

The Physics of Surface States with Interactions mediated by Bulk Properties, Defects and Surface Chemistry

 

Project Summary:

Progress in observing new physics in topological insulators (TIs), in particular in materials displaying interactions, requires a multidisciplinary effort. In our program we work on the discovery, growth, and fabrication of new materials that display new topologically-stabilized electronic states, studying both 3D crystals and thin films grown by Molecular Beam Epitaxy.

Those new materials are being characterized by many different experimental methods including high resolution and spin resolved photoemission spectroscopy, transport, and STM measurements, X-ray scattering, and electron microscopy. The materials of interest are particularly those that display interactions arising from the presence of magnetism, such as those based on the heavy metal iridium, and interactions of topological states with superconductivity. We are addressing new frontiers in physics, studying for example proximity induced superconductivity in TIs, the 3D TI superconductor CuxBi2Se3, band bending surface capacitance and screening in TIs, and the giant Rashba effect in BiTeI and related compounds. Further we are exploring theoretical frontiers in areas such as interactions of TI surface states with disorder and complex magnetic order, new topological phases in materials with weak indices, correlated insulators with diverse point group symmetries, and strongly correlated topologically ordered phases in small bandwidth materials.  

Our program includes the chemical modification of the surfaces of the TIs through molecular chemistry to create monolayers of dielectrics on the TI crystal surfaces, with the resulting species characterized by chemical spectroscopy. The correlation of the character of the chemically modified surfaces with the electronic properties is being performed. 

 

Sponsor: 

Army Research Office (ARO) Multidisciplinary University Research Initiative (MURI) program, grant W911NF-1-0461

ARO program managers: 

Marc Uhlrich

Marc Ulrich

 

Pani Varanasi

Pani Varanasi

ARO Triangle Park North Carolina