Dutta, Amit and Sen, Diptiman (2003) Gapless line for the anisotropic Heisenberg spin1/2 chain in a magnetic field and the quantum axial nextnearestneighbor Ising chain. In: Physical Review B (Condensed Matter and Materials Physics), 67 . 09443517.

PDF
Heisenberg_spin.pdf Download (84kB) 
Abstract
We study the anisotropic Heisenberg (XYZ) spin1/2 chain placed in a magnetic field pointing along the x axis. We use bosonization and a renormalization group analysis to show that the model has a nontrivial fixed point at a certain value of the XY anisotropy a and the magnetic field h. Hence there is a line of critical points in the (a,h) plane on which the system is gapless, even though the Hamiltonian has no continuous symmetry. The quantum critical line corresponds to a spinflip transition; it separates two gapped phases in one of which the Z2 symmetry of the Hamiltonian is broken. Our study has a bearing on one of the transitions of the axial nextnearest neighbor Ising chain in a transverse magnetic field. We also discuss the properties of the model when the magnetic field is increased further, in particular, the disorder line on which the ground state is a direct product of single spin states.
Item Type:  Journal Article 

Additional Information:  Copyright for this article belongs to American Physical Society (APS). 
Department/Centre:  Division of Physical & Mathematical Sciences > Centre for Theoretical Studies (Ceased to exist at the end of 2003) 
Depositing User:  L.Kaini Mahemei 
Date Deposited:  17 Sep 2004 
Last Modified:  19 Sep 2010 04:16 
URI:  http://eprints.iisc.ac.in/id/eprint/2049 
Actions (login required)
View Item 