  We study the phase structure and condensates of two-flavor QCD at finite
isospin chemical potential in the framework of a confining, Dyson-Schwinger
equation model. We find that the pion superfluidity phase is favored at high
enough isospin chemical potential. A new gauge invariant mixed quark-gluon
condensate induced by isospin chemical potential is proposed based on Operator
Product Expansion. We investigate the sign and magnitude of this new condensate
and show that it's an important condensate in QCD sum rules at finite isospin
density.
