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TT: Fachverband Tiefe Temperaturen

TT 33: Postersession Correlated Electrons: Metal Insulator Transition, Spin Systems and Itinerant Magnets

TT 33.17: Poster

Mittwoch, 25. März 2009, 14:00–18:00, P1A

Magnetic impurities in two-dimensional spin-1/2 antiferromagnets — •Björn Willenberg, Simon Grossjohann, and Wolfram Brenig — Institut für theoretische Physik, Technische Universität Braunschweig

Using Quantum Monte-Carlo methods based on the stochastic series expansion we investigate a single spin degree of freedom coupled to a two-dimensional Heisenberg antiferromagnet (HAFM). Results will be presented for thermodynamic and dynamic properties. In particular the local susceptibility will be considered as a function of temperature, magnetic field, and local spin quantum number. Moreover we will contrast the case of antiferro- versus ferromagnetic coupling of the impurity to the HAFM. This analysis will be extended to real-space spin correlation-functions which will be evaluated in the vicinity of the quantum impurity including a detailed finite size analysis. Finally the impurity dynamics will be considered by calculating imaginary time spin-correlators and performing Maximum Entropy analysis.