Shining a Light on Chiral Symmetry Breaking in Graphene
May 19, 2021•
Physics 14, 76
Sensitive photoemission measurements visualize the signatures of a symmetry-broken phase of graphene with carriers of mixed handedness.
C. Bao
Figure 1: (a) Graphene lattice and unit cell (orange diamond) highlighting the distinct A and B sublattices (inset). (b) Schematic of graphene pseudospin chirality around each Dirac point (
K and
Kʹ) in the graphene Brillouin zone (orange hexagon). (c) Graphene with a lattice of lithium atoms creating a new Kekulé-O bond pattern (purple diamond). (d) The Kekulé pattern results in the Dirac cones being superimposed on the new, smaller Kekulé Brillouin zone (purple hexagon). The new Dirac cones are simultaneously right and left handed and so no longer chiral.(a) Graphene lattice and unit cell (orange diamond) highlighting the distinct A and B sublattices (inset). (b) Schematic of graphene pseudospin chirality around each Dirac point (
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IMAGE: a, sketch of a system with an array of main resonance modes a m connected via a series of connecting modes c m^((n)), with the decay rate κ m^((n)); b, sketch of a. view more
Credit: by Xinyao Huang, Cuicui Lu, Chao Liang, Honggeng Tao, and Yong-Chun Liu
Optical nonreciprocity, which prohibits the light field returning along the original path after passing through the optical system in one direction, is not only of vast interest to fundamental science, which brings us a deeper understanding of Lorentz reciprocity, time-reversal symmetry, and topological effects, but is also of great importance for realizing nonreciprocal optical and electromagnetics devices such as isolators, circulator and directional amplifiers, which are indispensable for applications ranging from optical communication to optical information processing.