Comprehensive Anisotropic Linear Optical Properties of Weyl Semimetals, TaAs and NbAs

Abstract

TaAs and NbAs are two of the earliest identified Weyl semimetals that possess many intriguing optical properties, such as chirality-dependent optical excitations and giant second harmonic generation (SHG). Linear and nonlinear optics have been employed as tools to probe the Weyl physics in these crystals. Here we extend these studies to address two important points: determining the complete anisotropic dielectric response, and to explore if and how they can reveal essential Weyl physics. For the first time, we determine the complete anisotropic dielectric functions of TaAs and NbAs by combining spectroscopic ellipsometry and density functional theory (DFT). Parameterized Lorentz oscillators are reported from 1.2-6 eV (experiment) and 0-6 eV (DFT), and good agreement is shown between them. Both linear and nonlinear optical properties have been reported to reveal Weyl physics. We suggest that strong optical resonances from trivial bands are the likely origin of the large optical second harmonic generation previously reported at these energies. Furthermore, by comparing the contribution of a small k-space centered around the Weyl cones to the total linear dielectric function, we find that these contributions are highly anisotropic and are <25% of the total dielectric function below 0.5 eV; above 1eV, these contributions are negligible. Thus, the study of Weyl physics using optical techniques requires very low energies and even there, a careful assessment is required in distinguishing the much smaller contributions of the Weyl bands from the dominant contributions of the trivial bands and Drude response to the total dielectric function.

arXiv comment42 pages, 13 figures for the main text

References in corpus (34)

• Discovery of a Weyl Fermion Semimetal and Topological Fermi Arcs
• Experimental discovery of Weyl semimetal TaAs
• Theoretical Discovery/Prediction: Weyl Semimetal states in the TaAs material (TaAs, NbAs, NbP, TaP) class
• Observation of the chiral anomaly induced negative magneto-resistance in 3D Weyl semi-metal TaAs
• Ultrahigh mobility and giant magnetoresistance in the Dirac semimetal Cd${}_3$As${}_2$
• Weyl semimetal phase in non-centrosymmetric transition metal monophosphides
• Giant anomalous Hall effect in a ferromagnetic Kagome-lattice semimetal
• Negative magnetoresistance without well-defined chirality in the Weyl semimetal TaP
• Extremely large magnetoresistance and ultrahigh mobility in the topological Weyl semimetal NbP
• Observation of Weyl nodes in TaAs
• Giant anomalous Nernst effect and quantum-critical scaling in a ferromagnetic semimetal
• Giant anisotropic nonlinear optical response in transition metal monopnictide Weyl semimetals
• Experimental discovery of a topological Weyl semimetal state in TaP
• Direct optical detection of Weyl fermion chirality in a topological semimetal
• Electronic Transport and quantum oscillation of Topological Semimetals
• Giant room temperature anomalous Hall effect and magnetically tuned topology in the ferromagnetic Weyl semimetal Co2MnAl
• Criteria for directly detecting topological Fermi arcs in Weyl semimetals
• Optical Signatures of Weyl Points in TaAs
• Tantalum Monoarsenide: an Exotic Compensated Semimetal
• Electron scattering in tantalum monoarsenide
• Magnetotransport of single crystalline YSb
• Resonance-enhanced optical nonlinearity in the Weyl semimetal TaAs
• Magnetotransport of single crystalline NbAs
• Tracking ultrafast photocurrents in the Weyl semimetal TaAs using THz emission spectroscopy
• Electron-hole compensation effect between topologically trivial electrons and nontrivial holes in NbAs
• Optical Signatures of Dirac Nodal-lines in NbAs${}_2$
• Temperature-tunable Fano resonance induced by strong coupling between Weyl fermions and phonons in TaAs
• Optical Conductivity of Weyl Semimetals and Signatures of the Gapped Semimetal Phase Transition
• Coexistence of Weyl Physics and Planar Defects in Semimetals TaP and TaAs
• Non-stoichiometry and Defects in the Weyl Semimetals TaAs, TaP, NbP, and NbAs
• Optical signature of Weyl electronic structures in tantalum pnictides Ta$Pn$ ($Pn=$ P, As)
• Resonant optical second harmonic generation in graphene-based heterostructures
• Raman study of lattice dynamics in Weyl semimetal TaAs
• Linear and nonlinear optical probe of the ferroelectric-like phase transition in a polar metal, LiOsO3

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