The two-dimensional (2D) metal PtCoO2 is renowned for the lowest room temperature resistivity among all oxides, close to that of the top two materials Ag and Cu. In addition, we theoretically predict a strong intrinsic spin Hall effect. This originates from six strongly-tilted Dirac cones that we find in the electronic structure near the Fermi surface, where a gap is opened by large spin-orbit coupling (SOC). This is underpinned by rich topological properties; in particular, the phenomenology of a mirror Chern metal is realized not exactly, but very accurately, on account of an approximate crystalline symmetry. We expect that such 'vicinity topology' to be a feature of relevance well beyond this material. Our Wilson loop analysis indicates further elaborate features such as fragile topology. These findings highlight PtCoO2 as a promising material for spintronic applications as well as a platform to study the interplay of symmetry and topology.
@article{arxiv.1811.03105,
title = {Spin Hall effect in 2D metallic delafossite PtCoO$_2$ and vicinity topology},
author = {Sota Kitamura and Hidetomo Usui and Robert-Jan Slager and Adrien Bouhon and Veronika Sunko and Helge Rosner and Philip D. C. King and Joseph Orenstein and Roderich Moessner and Andrew P. Mackenzie and Kazuhiko Kuroki and Takashi Oka},
journal= {arXiv preprint arXiv:1811.03105},
year = {2018}
}