We employ angle resolved photoemission spectroscopy (ARPES) to investigate the Fermi surface of RuO2. We find a network of two Dirac nodal lines (DNL) as previously predicted in theory, where the valence- and conduction bands touch along continuous lines in momentum space. In addition, we find evidence for a third DNL close to the Fermi level which appears robust despite the presence of significant spin orbit coupling. We demonstrate that the third DNL gives rise to a topologically trivial flat-band surface state (FBSS) at the (110) surface. This FBSS can be tuned by surface doping and presents an interesting playground for the study of surface chemistry and exotic correlation phenomena.
@article{arxiv.1908.02621,
title = {The Dirac nodal line network in non-symmorphic rutile semimetal RuO$_2$},
author = {Vedran Jovic and Roland J. Koch and Swarup K. Panda and Helmuth Berger and Philippe Bugnon and Arnaud Magrez and Ronny Thomale and Kevin E. Smith and Silke Biermann and Chris Jozwiak and Aaron Bostwick and Eli Rotenberg and Domenico Di Sante and Simon Moser},
journal= {arXiv preprint arXiv:1908.02621},
year = {2019}
}