Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 14: Spin Systems and Itinerant Magnets

TT 14.6: Vortrag

Dienstag, 27. März 2007, 15:45–16:00, H19

Static Holes in the Geometrically Frustrated Bow-Tie Ladder — •Wolfram Brenig¹ and George Martins² — ¹Institut für Theoretische Physik, Technische Universität Braunschweig, D-38106 Braunschweig, Germany — ²Department of Physics, Oakland University, Rochester, MI 48309, U.S.A.

Doping of the geometrically frustrated bow-tie spin ladder with static holes is investigated by a complementary approach using exact diagonalization and hard-core quantum dimers. Results for the thermodynamics in the undoped case, the singlet density of states, the two-hole energy and the spin correlations will be presented. We find that the static holes polarize their vicinity by a localization of singlets in order to reduce the frustration. As a consequence the singlet polarization cloud induces short range repulsive forces between holes with oscillatory longer range behavior, which may lead to deconfinement. For those systems we have studied, most results for the quantum dimer approach agree qualitatively if not quantitatively with exact diagonalization. The ground state of the undoped system is non-degenerate with translationally invariant nearest-neighbor spin correlations up to the largest systems studied, consistent with a spin liquid state or a valence bond crystal with very large unit cell.