Bilayer graphene can become a fractional metal

It is known that electron interactions can cause a perfect spin polarization of the Fermi surface metal. In such situation only half non-interacting available, and thus this phase commonly referred to as 'half-metal'. Here we argue that, in multi-band electronic systems with nesting, further 'fractionalization' possible. Taking AA bilayer graphene convenient test case, demonstrate under suitable conditions imposed on interactions, doped host 'quarter-metal' state. state, one quarter (Fermi contour) reaches energy. At higher doping level, other 'fractional' metals emerge. We briefly analyze transport properties these proposed phases.