"Why are insulators insulating?"

Who: Raffaele Resta. Università di Trieste, Italy.

Place: Donostia International Physics Center. Pº Manuel Lardizabal 4, Donostia - San Sebastián

Date: Friday, 15 January 2016, 12:00

The insulating vs. conducting behavior of condensed matter is usually addressed
in terms of excitation spectra. At variance with such wisdom, W. Kohn showed in
1964 that the insulating state of matter also reflects a peculiar organization of the
electrons in their ground state.

The modern developments of the ?theory of the insulating state? started in 1999,
and continue to these days; at the root of these developments is the modern theory of
polarization, developed in the early 1990s, and based on geometrical concepts (Berry
phase). Since insulators and metals polarize in a qualitatively different way, the
theory of polarization has fundamental implications for the theory of the insulating
state as well. A common geometrical ?marker? caracterizes all insulators (band
insulators, Anderson insulators, Mott insulators, quantum Hall insulators. . . ) and
discriminates them from conductors.

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