|First Observation of Plasmarons in Graphene| An international
team of scientists performing angle-resolved photoemission
spectroscopy (ARPES) experiments at ALS Beamline 7.0.1 have
found that composite particles called plasmarons play a vital
role in determining graphene's properties. A plasmaron consists
of a charge carrier (electron or hole) coupled with a plasmon—an
electron density wave. Although plasmarons were proposed
theoretically in the late 1960s, and indirect evidence of them
has been found, this work is the first observation of their
distinct energy bands in graphene, or indeed in any material.
The discovery may hasten the day when graphene can be used for
"plasmonics" to build ultrafast computers—perhaps even room-
temperature quantum computers—plus a wide range of other tools
and applications. On the usual band-gap diagram of neutral
graphene, the filled valence band and the empty conduction band
are shown as two cones that meet at their tips at a point called
the Dirac crossing. This picture of