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TT: Fachverband Tiefe Temperaturen

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

TT 52.6: Vortrag

Donnerstag, 17. März 2011, 15:30–15:45, HSZ 105

Finite-size scaling analysis of the spatially anisotropic frustrated S=1/2 Heisenberg model — •Mohammad Siahatgar, Burkhard Schmidt, and Peter Thalmeier — Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden

We investigate the ground-state properties of the S=1/2 frustrated Heisenberg model on a 2D lattice with orthorhombic symmetry. This model, known as the J_1a,b−J₂ model, is studied using exact diagonalization technique on finite clusters, as well as introducing a systematic way to construct finite clusters to tile the square lattice. For this low symmetry model, a controlled procedure for the finite-size scaling analysis is defined for the tiles which are compatible with corresponding magnetic phase. We calculate the ground-state energy, structure factors and ordered moment, and compare these numerical results with spin-wave calculations as well. In particular, the finite-size behavior of the system in the disordered regions between ordered ferromagnetic and Néel and columnar antiferromagnetic phases is discussed more carefully. We conclude that the effect of spatial anisotropy J_1a,b is stabilizing the columnar antiferromagnetic order for all frustration parameters, notably in the spin-nematic phase of the isotropic model.