Phys. Rev. Lett. 103, 216801 (2009).
Coupled charge and valley excitations in graphene quantum Hall ferromegnets
Naokazu Shibata, and Kentaro Nomura
Phys. Rev. B 77, 235426 (2008)
Fractional quantum Hall effect in double-layer system
Fractional quantum Hall states in bilayer system at total filling
fraction $\nu=1/2$ are examined numerically under some ranges of the
layer separation and interlayer tunneling. It is shown that the ground
state changes continuously from two-component state to one-component
state as the interlayer tunneling rate is increased, while the lowest excited
state changes discontinuously. This fact explains observed unusual
behavior of the activation energy which reveals upward cusp as a
function of interlayer tunneling. Some trial wave functions for the
ground state and quasihole states are inspected.
ground state evolves continuously
quasihole states reveal level crossing
Kentaro Nomura and Daijiro Yoshioka
Gap evolution in nu=1/2 bilayer quantum Hall systems
J. Phys. Soc. Jpn. 73 2612 (2004).
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