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ECE Seminar: Matthew Grayson

"Topological Insulators: Electronic Materials for the Sorcerer's Apprentice"

March 30, 2011

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A revolution in electronic materials is currently underway, sparked by the discovery 5 years ago of a new class of conductors called topological insulators.

While neither a metal nor an insulator, this material harbors the properties of both, manifesting metallic surface states which surround its insulating semiconductor-like bulk. Almost magically, both conducting and insulating properties arise from the same intrinsic material but are defined according to context -- whether the material is found on the surface or bulk, respectively. For example, upon being cut in half, part of the bulk which used to be insulating instantly becomes metallic by virtue of the fact that it now exists on a surface boundary. Other remarkable properties of the surface states include locking the electron spin relative to the direction of motion. When coupled to magnetic layers and superconductors, it has been theoretically proposed to give rise to new types of resistanceless one-dimensional wires, particles which are their own anti-particle, and new paradigms for quantum computation. The underlying phenomena are manifest in the absence of any external fields and at room temperature. This talk will introduce these materials, survey the state of the art, and explain what work lies ahead to realize the promise of topological insulators as a novel electronic material.


Grayson is an expert on quantum electronic devices, quantum transport, and III-V semiconductor crystal growth. After earning his PhD from Princeton in Electrical Engineering, he had research appointments at U. Maryland as well as the Tech. Univ. Munich. His publications include quantum Hall (QH) edge tunneling spectroscopy, novel cleaved-edge overgrowth structures, quantum wires, corner overgrowth fabrication of bent quantum wells, the bent quantum Hall effect (invented by Grayson), and other novel III-V semiconductor crystal growth techniques. He holds a patent for thermoelectric computer chip sensors (pending), and a guest lectureship appointment at the Tech. Univ. of Munich, where he organizes the "Finding Nano" Summer Study Abroad Program for McCormick students. He also founded and produces the ETOPiA scientific theater outreach event each year, most recently featuring the play "QED" about Richard Feynman.