**Joint Physics Dept - MtSE Seminar**

**May 23rd, Tuesday (**SPECIAL
DAY**) **

**Topological
Edge States**

**Prof. Emil V. Prodan**

Yeshiva University

(Theoretical Condensed Matter
Physics, Host: Tyson)

****SPECIAL TIME: 2:45 pm - 3:45 pm with 2:30
pm tea time**

Room: **ECE 202 **

Topological Insulators and Superconductors are
fascinating states of matter displaying bulk electronic structures that cannot
be deformed into the ones of ordinary insulators, without crossing a quantum
phase transition. The “order parameter” of these phases is quantized and takes
the form of a topological invariant that can be computed from the ground state
of the system. This invariant is often, but not always, connected to a
macroscopic response such as the linear and non-linear Hall or magneto-electric
effects. If a boundary is cut to a topological insulator, necessarily a
metallic phase appears along this boundary. This metallic phase was conjectured
to remain conducting even in the presence of large disorder, hence evading the
phenomenon of Anderson localization which is prevalent in 1- and 2-dimensions.
In the first part of my talk, I will review all these concepts and discuss
various applications which makes these materials special. In the second part of
the talk, I will present specialized theoretical tools which enabled the
analysis of disordered topological insulators, hence computations of realistic
phase diagrams of various topological materials and a proof of their
bulk-boundary correspondence principle. Recently, these tools have been used to
predict new topological phases with unprecedented physical characteristics,
such as a display of quantized piezo-magneto-electric effect. These new
developments will be covered too.

**Biography:**** **Emil Prodan is a
professor of physics at Yeshiva University. His research combines mathematics
and large scale simulations to investigate the physics of complex materials.
Particularly, he has pioneered the use of operator algebras, K-theory and
non-commutative geometry in condensed matter theory. He is the author of two
monographs, “Bulk and Boundary Invariants for Complex Topological Insulators,”
and “A Computational Non-Commutative Geometry Program for Topological
Insulators,” both published by Springer. His research is supported by the NSF
CAREER award “Strong Disorder and Electron Interaction Effects in Topological
Insulators” and by the Keck Foundation award “Engineering New Materials Based
on Topological Phonon Edge Modes.” Emil received his PhD from Rice University,
where he performed pioneering large scale computer simulations of optical
absorption of nano-particles and, in parallel,
published fundamental results on the Kohn-Sham theory. He followed with a
postdoctoral position with Walter Kohn, the 1998 Nobel Laureate in Quantum
Chemistry, at UC Santa Barbara. Afterwards, Emil was elected fellow of the
Princeton Center for Complex Materials, where he worked Duncan Haldane, the
2016 Nobel Laureate in Physics, and Roberto Car. In 2007, Emil joined the
Physics Department of Yeshiva University.