Lorentz‐Boost‐Driven Magneto‐Optics in a Dirac Nodal‐Line Semimetal

Abstract

Optical response of crystalline solids is to a large extent driven by excitations that promote electrons among individual bands. This allows one to apply optical and magneto‐optical methods to determine experimentally the energy band gap —a fundamental property crucial to our understanding of any solid—with a great precision. Here it is shown that such conventional methods, applied with great success to many materials in the past, do not work in topological Dirac semimetals with a dispersive nodal line. There, the optically deduced band gap depends on how the magnetic field is oriented with respect to the crystal axes. Such highly unusual behavior is explained in terms of band‐gap renormalization driven by Lorentz boosts which results from the Lorentz‐covariant form of the Dirac Hamiltonian relevant for the nodal line at low energies.

Evidence for three-dimensional Dirac conical bands in TlBiSSe by optical and magneto-optical spectroscopy

“…Research on topological semimetals is an important part of modern condensed matter physics, in great part due to relativisticlike physics which may be observed in such systems [1][2][3]. An important class of topological semimetals are three-dimensional (3D) Dirac semimetals [4,5].…”

Evidence of 3D Dirac conical bands in TlBiSSe by optical and magneto-optical spectroscopy

“…Research on topological semimetals is an important part of modern condensed matter physics, in great part due to relativistic-like physics which may be observed in such systems [1][2][3]. An important class of topological semimetals are three-dimensional (3D) Dirac semimetals [4,5].…”