2011/04/30 by Fabien Trousselet, Giniyat Khaliullin, Peter Horsch · 39 citations
Physics and Astronomy · #Advanced Condensed Matter Physics #Atomic and Subatomic Physics Research #Condensed matter physics #Ferromagnetism #Heisenberg model #Physics #Physics of Superconductivity and Magnetism #Spin (aerodynamics) #Thermodynamics #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.84.054409
published in Physical Review B 84(5) (American Physical Society) · 13 pages, 10 figures
openalex publication_date 2011/08/02 · arxiv created 2011/09/22 · arxiv updated 2015/05/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We study the ground-state properties of the Kitaev-Heisenberg model in a magnetic field and explore the evolution of spin correlations in the presence of nonmagnetic vacancies. By means of exact diagonalizations, the phase diagram without vacancies is determined as a function of the magnetic field and the ratio between Kitaev and Heisenberg interactions. We show that, in the (antiferromagnetic) stripe-ordered phase, the static susceptibility and its anisotropy can be described by a spin canting mechanism. This accounts as well for the transition to the polarized phase when including quantum fluctuations perturbatively. Effects of spin vacancies depend sensitively on the type of the ground state. In the liquid phase, the magnetization pattern around a single vacancy in a small field is determined, and its spatial anisotropy is related to that of nonzero further neighbor correlations induced by the field and/or Heisenberg interactions. In the stripe phase, the joint effect of a vacancy and a small field breaks the sixfold symmetry of the model and stabilizes a particular stripe pattern. Similar symmetry-breaking effects occur even at zero field due to effective interactions between vacancies. This selection mechanism and intrinsic randomness of vacancy positions may lead to spin-glass behavior.