Searching for new states of matter and unusual quasiparticles in emerging
materials and especially low-dimensional systems is one of the major trends in
contemporary condensed matter physics. Dirac materials, which host
quasiparticles which are described by ultrarelativistic Dirac-like equations,
are of a significant current interest from both a fundamental and applied
physics perspective. Here we show that a pair of two-dimensional massless
Dirac-Weyl fermions can form a bound state independently of the sign of the
inter-particle interaction potential, as long as this potential decays at large
distances faster than Kepler's inverse distance law. This leads to the
emergence of a new type of energetically-favourable quasiparticle: bielectron
vortices, which are double-charged and reside at zero-energy. Their bosonic
nature allows for condensation and may give rise to Majorana physics without
invoking a superconductor. These novel quasiparticles arguably explain a range
of poorly understood experiments in gated graphene structures at low doping.Comment: 9 pages, 2 figure
