Doped kagome system as exotic superconductor

Abstract

A Chern-Simons theory for the doped spin-1/2 kagome system is constructed, from which it is shown that the system is an exotic superconductor that breaks time-reversal symmetry. It is also shown that the system carries minimal vortices of flux hc/4e (as opposed to the usual hc/2e in conventional superconductors) and contains fractional quasiparticles (including fermionic quasiparticles with semionic mutual statistics and spin-1/2 quasiparticles with bosonic self-statistics) in addition to the usual spin-1/2 fermionic Bogoliubov quasiparticles. Two Chern-Simons theories—one with an auxiliary gauge field kept and one with the auxiliary field and a redundant matter field directly eliminated—are presented and shown to be consistent with each other.