Second-order Peierls transition in the spin-orbital Kumar-Heisenberg model

Wojciech Brzezicki, Imre Hagymási, Jacek Dziarmaga, O. Legeza

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

We add a Heisenberg interaction term λ in the one-dimensional SU(2) - XY spin-orbital model introduced by Kumar. At λ=0 the spin and orbital degrees of freedom can be separated by a unitary transformation leading to an exact solution of the model. We show that a finite λ>0 leads to spontaneous dimerization of the system which in the thermodynamic limit becomes a smooth phase transition at λ→0, whereas it remains discontinuous within the first-order perturbation approach. We present the behavior of the entanglement entropy, energy gap, and dimerization order parameter in the limit of λ→0 confirming the critical behavior. Finally, we show the evidence of another phase transition in the Heisenberg limit, λ→ and give a qualitative analytical explanation of the observed dimerized states both in the limit of small and large λ.

Original languageEnglish
Article number205137
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume91
Issue number20
DOIs
Publication statusPublished - May 27 2015

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Dimerization
Phase transitions
orbitals
dimerization
Energy gap
Entropy
Thermodynamics
degrees of freedom
entropy
perturbation
thermodynamics
interactions

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

Cite this

Second-order Peierls transition in the spin-orbital Kumar-Heisenberg model. / Brzezicki, Wojciech; Hagymási, Imre; Dziarmaga, Jacek; Legeza, O.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 91, No. 20, 205137, 27.05.2015.

Research output: Contribution to journalArticle

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