2018/03/31 by Jianfeng Wang, Yizhou Liu, Kyung‐Hwan Jin +6 · 38 citations
Materials Science · Physics and Astronomy · #Band gap #Biology #Condensed matter physics #Dirac (video compression format) #Geology #Graphene research and applications #NODAL #Physics #Quantum Mechanics and Non-Hermitian Physics #Quantum mechanics #Semimetal #Topological Materials and Phenomena #cond-mat.mes-hall #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.98.201112
published in Physical review. B./Physical review. B 98(20) (American Physical Society) · 10 pages, 3 figures, 1 table
arxiv created 2018/08/22 · openalex created_date 2018/08/31 · openalex publication_date 2018/11/26 · arxiv updated 2018/12/05 · openalex updated_date 2026/08/05
Topological semimetals (TSMs) in which conduction and valence bands cross at zero-dimensional (0D) Dirac nodal points (DNPs) or 1D Dirac nodal lines (DNLs), in 3D momentum space, have recently drawn much attention due to their exotic electronic properties. Here, we generalize the TSM state further to a higher-dimensional Dirac nodal sphere (DNS) or pseudo DNS (PDNS) state, with the band crossings forming a 2D closed or approximate sphere at the Fermi level. This TSM state can exhibit unique electronic properties, making DNS/PDNS a type of fermion beyond the DNP/DNL paradigm. In realistic crystals, we demonstrate two possible types of PDNS states underlain by different crystalline symmetries, which are characterized with a spherical backbone consisting of multiple DNLs and approximate band degeneracy in between the DNLs. We identify all the possible band crossings with pairs of 1D irreducible representations to form the PDNS states in 32 point groups. Importantly, we discover that strained MH3 (M=Y, Ho, Tb, Nd) and Si3N2 are material candidates to realize these two types of PDNS states, respectively. As a high-symmetry-required state, the PDNS semimetal can be regarded as the ``parent phase'' for other topological gapped and gapless states.