1999/11/07 by K. Takano, Ken'ichi Takano
Chemistry · Mathematics · Physics and Astronomy · #Chemistry #Condensed matter physics #Crystallography #Exchange interaction #Ferromagnetism #Frustration #Hamiltonian (control theory) #Mathematical physics #Mathematics #Nonlinear system #Phase (matter) #Phase diagram #Physics #Physics of Superconductivity and Magnetism #Quantum many-body systems #Quantum mechanics #Spins #Theoretical and Computational Physics #cond-mat.stat-mech #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.61.8863
9 pages (8 figures included)
arxiv created 1999/11/07 · openalex publication_date 2000/04/01 · openalex created_date 2016/06/24 · arxiv updated 2016/08/31 · openalex updated_date 2026/08/05
We study mixed quantum spin chains consisting of two kinds of spins with magnitudes sa and sb. The spins are arrayed as sa\ensuremath-sa\ensuremath-sb\ensuremath-sb in a unit cell and the exchange couplings are accordingly periodic with period 4. The spin Hamiltonian is mapped onto a nonlinear \ensuremathσ model based on the general formula for periodic inhomogeneous spin chains. The gapless condition given by the nonlinear \ensuremathσ model determines boundaries between disordered phases in the space of the exchange parameters. The phase diagram has a rich phase structure characterized by the values of sa and sb. We explain all phases in the singlet-cluster-solid picture which is an extension of the valence-bond-solid picture.