Spin symmetry breaking in bilayer quantum Hall systems

Based on the construction of generalized Halperin wave functions, we predic t the possible existence of a large class of broken spin symmetry states in bilayer quantum Hall structures, generalizing the recently suggested cante d antiferromgnetic phase to many fractional fillings. We develop the approp riate Chem-Simons theory, and establish explicitly that the low-lying neutr al excitation is a Goldstone mode and that the charged excitations are bime rons with continuously tunable (through the canted antiferromagnetic order parameter) electric charge on the individual merons.