1202.5389 (Eun-Gook Moon)

Skyrmions with quadratic band touching fermions: A way to achieve charge
4e superconductivity    [PDF]

Eun-Gook Moon

We study Skyrmion quantum numbers, charge and spin, in (2+1) dimension
induced by quadratic band toucing(QBT) fermions. It is shown that induced
charge of Skyrmions is twice bigger than corresponding Dirac particles' and
their statistics are always bosonic. Applying to Bernal stacking bi-layer
graphene, we show that Skyrmions of quantum spin Hall(QSH) are charge 4e
bosons, so its condensation realizes charge $4e$ superconductivity(SC). One
candidate for a critical theory of the phase transition is non linear sigma
model with Wess-Zumino-Witten term, and we calculate renormalization group beta
function of the model perturbatively and show its phase diagram. We also
discuss how QBT fermion is different from two copies of Dirac particles.

View original: http://arxiv.org/abs/1202.5389