Home >  研究会等 > Multipole moments and fractional corner charges of insulating materials

Multipole moments and fractional corner charges of insulating materials

日程 : 2020年11月27日(金) 16:00 - 17:00 場所 : Zoom 開催(事前登録を下記リンク先にてお願い致します) 講師 : Prof. Haruki Watanabe 所属 : 東京大学 世話人 : 押川 正毅 (63275)
e-mail: oshikawa@issp.u-tokyo.ac.jp

How do we characterize and classify the insulating states of matter? Recent advances in the topological approach in condensed-matter physics offer a classification based on the winding and the quantum entanglement in the ground-state wavefunction. Although a nontrivial bulk topology is usually manifested as anomalous surface states, gapless modes are localized to the hinges and corners of the sample in the case of “higher-order” topology.

In this talk, we discuss that even absolutely topologically trivial materials may exhibit fractional charges on their corners and hinges. To predict these boundary signatures from the bulk, we develop a general formulation of bulk multipole moments, directly generalizing the “modern theory” formulation of the bulk polarization. As an example, we discuss e/8 fractional corner charges of grains of “table salt” and propose their direct measurement using atomic force microscopy.

Refs:
HW and S. Ono, Phys. Rev. B 102, 165120 (2020)
HW and H. C. Po, arXiv:2009.04845.


(公開日: 2020年11月16日)