Renormalization group study of electromagnetic interaction in multi-Dirac-node systems.
Theory of a quantum critical phenomenon in a topological insulator: (3 + 1)-dimensional quantum electrodynamics in solids. Weyl semimetal in a topological insulator multilayer. Variation of charge dynamics in the course of metal–insulator transition for pyrochlore type Nd2Ir2O7. Topological semimetal and Fermi-arc surface states in the electronic structure of pyrochlore iridates. Topological order: From long-range entangled quantum matter to a unified origin of light and electrons. Quantum Phase Transitions 2nd edn (Cambridge Univ. The interplay between the anisotropic dispersion and the Coulomb interaction brings about a screening phenomenon distinct from the conventional Thomas–Fermi screening in metals and logarithmic screening in Dirac fermions. At the quantum critical point, the emerging low-energy fermions, dubbed the anisotropic Weyl fermions, show both relativistic and Newtonian dynamics simultaneously. Here we discover a class of quantum critical phenomena in topological materials for which either the inversion symmetry or time-reversal symmetry can be broken. In conventional topological insulators in three dimensions, the low-energy theory near the gap-closing point can be described by relativistic Dirac fermions coupled to the long-range Coulomb interaction hence, the quantum critical point of topological phase transitions provides a promising platform to test the intriguing predictions of quantum electrodynamics. In that case, replace Q by Q/ε, where ε is the relative permittivity due to these other contributions.Topological phase transitions in condensed matter systems accompany emerging singularities of the electronic wavefunction, often manifested by gap-closing points in momentum space. Note that there may be dielectric permittivity in addition to the screening discussed here for example due to the polarization of immobile core electrons. With k 0=0 (no screening), this becomes the familiar Coulomb's law. The Thomas-Fermi wavevector (in Gaussian-cgs units) is k 0 2 = 4 π e 2 ∂ n ∂ μ ( cgs-Gaussian) It is a special case of the more general Lindhard theory in particular, Thomas–Fermi screening is the limit of the Lindhard formula when the wavevector (the reciprocal of the length-scale of interest) is much smaller than the fermi wavevector, i.e. Thomas–Fermi screening is a theoretical approach to calculating the effects of electric field screening by electrons in a solid.
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