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TT: Fachverband Tiefe Temperaturen
TT 44: Poster Session Correlated Electrons
TT 44.84: Poster
Thursday, March 17, 2011, 10:00–13:00, P1
Generalized Magnetic Impurities in Low-Dimensional Quantum Antiferromagnets — •Björn Willenberg1,3, Wolfram Brenig1,3, Holger Frahm2,3, and Eric Jeckelmann2,3 — 1Institute for Theoretical Physics, Technische Universität Braunschweig — 2Institute for Theoretical Physics, Leibniz Universität Hannover — 3Niedersächsische Technische Hochschule, NTH
We investigate magnetic impurities with extended multiplet structure in contact with spin-1/2 antiferromagnets. First, and using Quantum Monte-Carlo methods based on the stochastic series expansion, we study a spin-1/2 dimer coupled to the two-dimensional (2D) Heisenberg antiferromagnet (HAFM) at finite temperature. Results will be presented for thermodynamic properties as a function of temperature, exchange-coupling constants, and magnetic field. These include the impurity susceptibilities, magnetization, and the static on- and off-dimer correlation functions. Our findings will be contrasted against those for single spin-1/2 impurities in 2D HAFMs. Moreover we will analyze similar properties for S>1/2 edge-spins coupled to 1D HAFMs with open boundary conditions, where a comparison with results from Bethe ansatz and density-matrix renormalization methods is possible in the limit of zero temperature.
Work partially funded by the NTH School for Contacts in Nanosystems.