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 $\nu =2\mathrm{}$ in a tilted magnetic field using capacitance spectroscopy. The competition between two ground states is found at the Zeeman splitting appreciably smaller than the symmetric-antisymmetric splitting. Although 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 interpret the obtained results in terms of a predicted canted antiferromagnetic phase.