David Hsieh, Pappalardo Fellow in Physics, MIT
The topological insulator is a new electronic phase of matter that exhibits quantum-Hall-like properties even in the absence of a magnetic field. They are realized in strongly spin-orbit coupled band insulators and support surface states that behave like massless helical Dirac fermions. In this talk, I will describe how spin- and angle-resolved photoemission spectroscopy was used to discover the first topological insulator in a BiSb random alloy and subsequently identify new generations of topological insulators based on stoichiometric binary and ternary compounds. I will then discuss more recent results showing how ultrafast laser pulses can be used to visualize detailed spin textures in topological insulators and to excite spin-polarized currents for potential device applications.