Dynamical mean-field theory for quantum spin systems: Test of solutions for magnetically ordered states

Junya Otsuki, Yoshio Kuramoto

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

A spin version of dynamical mean-field theory is extended for magnetically ordered states in the Heisenberg model. The self-consistency equations are solved with high numerical accuracy by means of the continuous-time quantum Monte Carlo with bosonic baths coupled to the spin. The resultant solution is critically tested by known physical properties. In contrast with the mean-field theory, soft paramagnons appear near the transition temperature. Moreover, the Nambu-Goldstone mode (magnon) in the ferromagnetic phase is reproduced reasonably well. However, antiferromagnetic magnons have an energy gap in contradiction to the Nambu-Goldstone theorem. The origin of this failure is discussed in connection with the artificial first-order nature of the transition.

Original languageEnglish
Article number024427
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume88
Issue number2
DOIs
Publication statusPublished - 2013 Jul 30

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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