Topological phase transitions understood via the polarization amplitude

Balasz Hetenyi
Bilkent University, Ankara
Özet: Topological systems are one of the most active research areas in condensed matter physics.  The topological characterization of a condensed matter system relies on mathematical constructs such as the Berry phase, the winding number, or the Chern number.  In the first part of the talk, I will explain how the Berry phase can be understood as the first cumulant of a series. The cumulants themselves are derived from the polarization amplitude, a quantity introduced decades ago in the context of the Berry phase theory of polarization, and one which has received attention recently.   We calculate higher order cumulants and reconstruct the underlying distribution of the polarization for the Rice-Mele model.  Our approach allows the visualization of a topological transition, how a system goes between phases with different quantization. In the second part of the talk, I will go through constructing one-dimensional analogs of the Haldane and Kane-Mele models.  In the end, I will discuss the application of our cumulant method to an interacting model.
 
Yer: MSGSÜ Bomonti Binası, Fizik Bölümü
Tarih: 14 Mart 2019 Perşembe, 15.00