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arXiv · 2304.13086

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

Bikash Patra·Rahul Verma·Shin-Ming Huang·Bahadur Singh
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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 $Tm~d$ 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.

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Bikash Patra, Rahul Verma, Shin-Ming Huang, Bahadur Singh. 2023-04-25. Role of effective mass anisotropy in realizing a hybrid nodal-line fermion state. https://doi.org/10.1103/physrevb.108.235136

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