Sen, D and Lal, S (2000) One-dimensional fermions with incommensuration close to dimerization. In: EPL: Europhysics Letters, 52 (3). pp. 337-343.
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We study a model of fermions hopping on a chain with a weak incommensuration close to dimerization; both q, the deviation of the wave number from pi, and delta, the strength of the incommensuration, are assumed to be small. For free fermions, we show that there are an infinite number of energy bands which meet at zero energy as q approaches zero. The number of states lying inside the q = 0 gap remains nonzero as q/delta --> 0. Thus the limit q --> 0 differs from q = 0, as can be seen clearly in the low-temperature specific heat. For interacting fermions or the XXZ spin-(1/2) chain, we use bosonization to argue that similar results hold. Finally, our results can be applied to the Azbel-Hofstadter problem of particles hopping on a two-dimensional lattice in the presence of a magnetic field.
|Item Type:||Journal Article|
|Additional Information:||Copyright of this article belongs to EDP Sciences.|
|Department/Centre:||Division of Physical & Mathematical Sciences > Centre for Theoretical Studies|
|Date Deposited:||04 Aug 2010 07:11|
|Last Modified:||19 Sep 2010 06:13|
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