Sen, Diptiman and Lal, Siddhartha (1998) Onedimensional fermions with incommensurate hopping close to dimerization. [Preprint]

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Abstract
We study the spectrum 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 small. For free fermions, we use a continuum Dirac theory to show that there are an infinite number of bands which meet at zero energy as q approaches zero. In the limit that the ratio q/delta > 0, the number of states lying inside the q = 0 gap is nonzero and equal to 2 delta / pi^2. Thus the limit q > 0 differs from q = 0; this can be seen clearly in the behavior of the specific heat at low temperature. For interacting fermions or the XXZ spin1/2 chain, we use bosonization to argue that similar results hold.
Item Type:  Preprint 

Additional Information:  Europhys.Lett. 52 (2000) 337343 
Keywords:  Strongly Correlated Electrons 
Department/Centre:  Division of Physical & Mathematical Sciences > Centre for Theoretical Studies (Ceased to exist at the end of 2003) 
Date Deposited:  13 Aug 2004 
Last Modified:  19 Sep 2010 04:13 
URI:  http://eprints.iisc.ac.in/id/eprint/816 
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