Optical phonon dynamics and electronic fluctuations in the Dirac semimetal Cd3As2

Abstract

Raman scattering in the three-dimensional Dirac semimetal Cd3As2 shows an intricate interplay of electronic and phonon degrees of freedom. We observe resonant phonon scattering due to interband transitions, an anomalous anharmonicity of phonon frequency and intensity, as well as quasielastic (E~0) electronic scattering. The latter two effects are governed by a characteristic temperature scale T* ~ 100 K that is related to mutual fluctuations of lattice and electronic degrees of freedom. A refined analysis shows that this characteristic temperature corresponds to the energy of optical phonons which couple to interband transitions in the Dirac states of Cd3As2. As electron-phonon coupling in a topological semimetal is primarily related to phonons with finite momenta, the back action on the optical phonons in only observed as anharmonicities via multi-phonon processes involving a broad range of momenta. The resulting energy density fluctuations of the coupled system have previously only been observed in low dimensional or frustrated spin systems with suppressed long range ordering.

9 pages

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• Evidence for dominant phonon-electron scattering in Weyl semimetal WP${}_2$
• Weakly Interacting Topological Insulators: Quantum Criticality and Renormalization Group Approach
• Widely Tunable Optical and Thermal Properties of Dirac Semimetal Cd${}_3$As${}_2$
• Probing lattice dynamics and electron-phonon coupling in topological nodal-line semimetal ZrSiS
• Non-uniform carrier density in Cd${}_3$As${}_2$ evidenced by optical spectroscopy
• Topological phase transition between distinctWeyl semimetal states in MoTe2
• Indications for Lifshitz transitions in the nodal-line semimetal ZrSiTe induced by interlayer interaction
• Population inversion and Dirac fermion cooling in 3D Dirac semimetal Cd${}_3$As${}_2$
• A supervised learning algorithm for interacting topological insulators based on local curvature
• Effect of topology on quasi-particle interactions in the Weyl semimetal WP${}_2$
• Non-trivial phonon dynamics and significant electron-phonon coupling of the high frequency modes in a Dirac semimetal
• Doping effects on charge density instability in non-centrosymmetric PbxTaSe2
• Evidences for local non-centrosymmetricity and strong phonon anomaly in EuCu2As2: A Raman spectroscopy and lattice dynamics study
• Exploring Spectral Singularities in Dirac Semimetals: The Role of Non-Hermitian Physics and Dichroism