Canted antiferromagnetic phase in a double quantum well in a tilted quantizing magnetic field

We investigate the double-layer electron system in a parabolic quantum well at filling factor v = 2 in a tilted magnetic field using capacitance spect roscopy. The competition between two ground states is found at the Zeeman s plitting appreciably smaller than the symmetric-antisymmetric splitting. Al though at the transition point the system breaks up into domains of the two competing states, the activation energy turns out to be finite, signaling the occurrence of a new insulator-insulator quantum phase transition. We in terpret the obtained results in terms of a predicted canted antiferromagnet ic phase.