Effect of an in-plane magnetic field on magnetic phase transitions in nu=2bilayer quantum Hall systems

By using the effective bosonic spin theory, which was recently proposed by Demler and Das Sarma [Phys. Rev. Lett. 82, 3895 (1999)], we analyze the eff ect of an external in-plane magnetic field on the magnetic phase transition s of the bilayer quantum Hall system at filling factor nu=2. It is found th at the quantum phase diagram is modified by the in-plane magnetic field. Th erefore, quantum phase transitions can be induced simply by tilting the mag netic field. The general behavior of the critical tilted angle for differen t layer separations and interlayer tunneling amplitudes is shown. We find t hat the critical tilted angles being calculated agree very well with the re ported values. Moreover, a universal critical exponent for the transition f rom the canted antiferromagnetic phase to the ferromagnetic phase is found to be equal to 1/2 within the present effective theory. [S0163-1839(99)5084 4-8].