  Resistively detected nuclear magnetic resonance (NMR) is observed inside the
ring-like structure, with a quantized Hall conductance of 6e^2/h, in the phase
diagram of a two subband electron system. The NMR signal persists up to 400 mK
and is absent in other states with the same quantized Hall conductance. The
nuclear spin-lattice relaxation time, T1, is found to decrease rapidly towards
the ring center. These observations are consistent with the assertion of the
ring-like region being a ferromagnetic state that is accompanied by collective
spin excitations.
