Abhay Pasupathy, Associate Professor of Physics, Columbia University
The iron pnictides are a class of high-temperature superconductors whose essential structure consists of a nearly square plane of iron and arsenic atoms. Nearly all of these materials display electronic properties that break the square symmetry of the lattice, a phenomenon termed electronic nematicity. What drives this nematic behavior? Can it be controlled using an external field? Is it related to superconductivity? In this talk, I will discuss answers to these questions based on scanning tunneling microscopy measurements that directly visualize the nematic electronic states in one particular family of the pnictides. I will show that nematicity is intimately related to both magnetism and superconductivity in these materials, and describe experiments where uniaxial strain can be used to control the nematic behavior in these (and potentially other) compounds.