Insight into the Topological Nodal Line Metal YB₂ with Large Linear Energy Range: A First-Principles Study

• Main Authors: Yang Li, Jihong Xia, Rabah Khenata, Minquan Kuang
• Format: Article
• Language: English
• Published: MDPI AG 2020-08-01
• Series: Materials
• Subjects: YB₂; linear band crossing; topological metal; spin–orbit coupling; phonon dispersion; electronic structure
• Online Access: https://www.mdpi.com/1996-1944/13/17/3841

The presence of one-dimensional (1D) nodal lines, which are formed by band crossing points along a line in the momentum space of materials, is accompanied by several interesting features. However, in order to facilitate experimental detection of the band crossing point signatures, the materials must possess a large linear energy range around the band crossing points. In this work, we focused on a topological metal, YB₂, with phase stability and a <i>P6/mmm</i> space group, and studied the phonon dispersion, electronic structure, and topological nodal line signatures via first principles. The computed results show that YB₂ is a metallic material with one pair of closed nodal lines in the <i>k_z</i> = 0 plane. Importantly, around the band crossing points, a large linear energy range in excess of 2 eV was observed, which was rarely reported in previous reports that focus on linear-crossing materials. Furthermore, YB₂ has the following advantages: (1) An absence of a virtual frequency for phonon dispersion, (2) an obvious nontrivial surface state around the band crossing point, and (3) small spin–orbit coupling-induced gaps for the band crossing points.