Role of effective mass anisotropy in realizing a hybrid nodal-line fermion state

Abstract

Understanding the role of lattice geometry in shaping topological states and their properties is of fundamental importance to condensed matter and device physics. Here we demonstrate how an anisotropic crystal lattice drives a topological hybrid nodal line in transition metal tetraphosphides $Tm$P${}_4$ ($Tm$ = Transition metal). $Tm$P${}_4$ constitutes a unique class of black phosphorus materials formed by intercalating transition metal ions between the phosphorus layers without destroying the characteristic anisotropic band structure of the black phosphorous. Based on the first-principles calculations and $k\cdot p$ theory, we show that $Tm$P${}_4$ harbor a single hybrid nodal line formed between oppositely-oriented anisotropic $Tmd$ and P states unhinged from the high-symmetry planes. The nodal line consists of both type-I and type-II nodal band crossings whose nature and location are determined by the effective-mass anisotropies of the intersecting bands. We further discuss a possible topological phase transition to exemplify the formation of the hybrid nodal line state in $Tm$P${}_4$. Our results offer a comprehensive study for understanding the interplay between structural motifs-driven mass anisotropies and topology in anisotropic lattice materials to realize hybrid semimetal states.

References in corpus (6)

• Topological Crystalline Insulators
• The space group classification of topological band insulators
• Hybrid Weyl Semimetal
• Electric-field tunable Dirac semimetal state in phosphorene thin films
• Topological crystalline insulator state with type-II Dirac fermions in transition metal dipnictides
• High-Pressure Synthesis of a Massive and Non-Symmorphic Dirac Semimetal Candidate MoP${}_4$

Cited by in corpus (1)

• The orbital-driven topological phase transition and planar Hall responses in ternary tellurides Weyl semi-metals