Dresden 2011 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 52: CE: Low-dimensional Systems - Models 1

TT 52.3: Vortrag

Donnerstag, 17. März 2011, 14:30–14:45, HSZ 105

Ground states with spontaneous breaking of translational symmetry in orthogonal-dimer chain with Ising and Heisenberg bonds — •Vadim Ohanyan¹ and Andreas Honecker² — ¹Department of Theoretical Physics, Yerevan State University, Alex Manoogian 1, 0025, Yerevan, Armenia — ²Institut für Theoretische Physik Universität Göttingen, Friedrich-Hund-Platz 1 37077 Göttingen, Germany

Considering the exactly solvable model of orthogonal-dimer chain with Ising and Heisenberg bond we investigate the issue of vast variety of its ground states, especially ones with spontaneous breaking of the translational symmetry. Analyzing ground states properties we obtain several T=0 ground states phase diagrams which correspond to different sets of the parameters. We demonstrate the appearance of magnetization plateaus at M/M_sat=0,1/4 which are connected with the breaking of translational symmetry of the lattice, more precisely, with the doubling of unit cell. The general mechanism of unit cell doubling in the lattice models with block structure and left-right asymmetry is discussed. Calculating the partition function exactly we also obtain analytic expressions for the free energy and all thermodynamic function, presenting the plots of magnetization processes for finite temperature which displays the magnetization plateaus at M/M_sat=0,1/4,1/2.