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HL: Fachverband Halbleiterphysik

HL 5: Topological insulators

HL 5.12: Vortrag

Montag, 1. April 2019, 12:30–12:45, H36

Higher-order topology in two-dimensional crystals — Frank Schindler¹, Wladimir A. Benalcazar^2,3, Marta Brzezinska^1,4, Mikel Iraola^5,6, Adrien Bouhon^7,8, •Stepan S. Tsirkin¹, Maia G. Vergniory^5,9, and Titus Neupert¹ — ¹University of Zürich, Switzerland — ²Pennsylvania State University, USA — ³University of Illinois at Urbana-Champaign, USA — ⁴Wroclaw University of Science and Technology, Poland — ⁵Donostia International Physics Center, Donostia - San Sebastian, Spain — ⁶University of the Basque Country UPV/EHU, Bilbao, Spain — ⁷Uppsala University, Sweden — ⁸NORDITA, Stockholm, Sweden — ⁹IKERBASQUE, Basque Foundation for Science, Bilbao, Spain

We study two-dimensional spinful topological phases of matter protected by time-reversal and crystalline symmetries. To define the topology we employ the concept of corner charge fractionalization: We show that corners in a higher-order topological phase can carry charges that are fractions of even multiples of the electric charge. These charges are quantized and topologically stable as long as all symmetries are preserved. We classify the topologies corresponding to different corner charge configurations for all 80 layer groups, and present their bulk topological indices. These can be calculated from the symmetry data and Brillouin zone Wilson loops. To corroborate our findings, we present tight-binding models and density functional theory calculations for various material realizations.