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What is the significance of the "quantum Hall effect" observed in graphene ?

  • A.It indicates the presence of a bandgap in graphene
  • B.It demonstrates the unique behavior of charge carriers in graphene
  • C.It signifies the low thermal conductivity of graphene
  • D.It is unrelated to the electronic properties of graphene

Answer: B

The quantum Hall effect in graphene demonstrates the unique behavior of charge carriers in graphene.

In 2005 graphene was found to show an unusual, 'half-integer' quantum Hall effect, with plateaus in Hall conductivity at \(4(n + 1/2)e^{2}/h\). This comes from its electrons behaving as massless Dirac fermions with a linear energy-momentum relation and a Berry phase of \(\pi\). In graphene the effect can even be seen at room temperature in strong fields.

It does not indicate a bandgap; pristine graphene is gapless. It has nothing to do with thermal conductivity, which in graphene is in fact very high. And it is directly tied to graphene's electronic properties, so the last option is wrong.

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