Discovery of Dirac nodal loop in non-symmorphic semimetal Nb₃SiTe₆
Ro-Ya Liu1*, Angus Huang2,3, Chih-Chuan Su4, Raman Sankar4, Shih-Chang Weng1, Meng-Kai Lin5, Peng Chen6, Joseph Andrew Hlevyack5, Alexei Fedorov7, Cheng-Maw Cheng1, Jonathan Denlinger7, Chia-Seng Chang4, Horng-Tay Jeng8, Tien-Ming Chuang4, Tai-Chang Chiang5
1NSRRC, Scientific Research Division, Hsinchu City, Taiwan
2Center for quantum technology, National Tsing-Hua University, Hsinchu City, Taiwan
3Dept. of Physics, National Cheng Kung University, Tainan City, Taiwan
4Institute of Physics, Academia Sinica, Taipei City, Taiwan
5Dept. of Physics, University of Illinois at Urbana-Champaign, Urbana, USA
6School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
7Advanced light source, Lawrence Berkeley National Lab, Berkeley, USA
8Dept. of Physics, National Tsing-Hua University, Hsinchu City, Taiwan
* Presenter:Ro-Ya Liu,
Fermions in hourglass semimetals attract a lot of attention recently. In 3-dimensional
non-symmorphic crystal, the essential band crossing protected by translational
symmetry hosts Dirac nodal loops in a 2-dimensional k-surface. These Dirac nodal
loops at lateral surfaces are the origin of many unusual properties in transport or
optical response, such as anisotropic electron transport, and chiral anomaly. We report
herein a detailed study of a non-symmorphic crystal, Nb 3 SiTe 6 by using angle-
resolved photoemission spectroscopy. Band dispersion along XS is mapped out by
varying photon energies. The crossing point (Dirac point) of a Dirac cone gradually
shifts to higher binding energy with the change of k z from X to S point. The energy
shift provides straightforward evidence for Dirac nodal loop.

Keywords: Hourglass semimetal, Dirac nodal loop, Angle-resolved photoemission spectroscopy