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تسجيل مستخدم جديدTopological Transition of Graphene from Quantum Hall Metal to Quantum Hall Insulator at $ u=0$
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The puzzle of recently observed insulating phase of graphene at filling factor $ u=0$ in high magnetic field quantum Hall (QH) experiments is investigated. We show that the magnetic field driven Peierls-type lattice distortion (due to the Landau level degeneracy) and random bond fluctuations compete with each other, resulting in a transition from a QH-metal state at relative low field to a QH-insulator state at high enough field at $ u=0$. The critical field that separates QH-metal from QH-insulator depends on the bond fluctuation. The picture explains well why the field required for observing the insulating phase is lower for a cleaner sample.
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