Regensburg 2019 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 5: Topological insulators
HL 5.12: Talk
Monday, April 1, 2019, 12:30–12:45, H36
Higher-order topology in two-dimensional crystals — Frank Schindler1, Wladimir A. Benalcazar2,3, Marta Brzezinska1,4, Mikel Iraola5,6, Adrien Bouhon7,8, •Stepan S. Tsirkin1, Maia G. Vergniory5,9, 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.