How can one localize the massless fermions in Dirac materials?

I noticed that finite electric potential cannot localize the low energy excitations in a graphene sheet. Is it possible to localize the massless fermions in the surface band of topological insulators with a magnetic field?

I found a paper dealing with a similar problem: http://apl.aip.org/resource/1/applab/v98/i16/p162101_s1

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What do you mean "localize"? Do you mean make bound states? –  Ron Maimon Sep 16 '11 at 19:02
Yes. That is what I mean. –  Z.Sun Sep 16 '11 at 19:50