A. Raoux, M. Morigi, J. N. Fuchs, F. Piéchon, G. Montambaux
We study the orbital susceptibility of coupled energy bands with a pair of Dirac points, as in graphene. We show that different systems having the same zero-field energy spectrum exhibit strong differences in their orbital magnetic response at zero energy, ranging from diamagnetism (graphene) to paramagnetism (dice lattice). A lattice model is introduced which interpolates continuously between these two limits. This striking behavior is related to a Berry phase varying continuously from pi to 0. These predictions could be tested with cold atoms in an optical lattice
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http://arxiv.org/abs/1306.6824
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