{"id":{"repo_id":"aachen","oai_identifier":"oai:publications.rwth-aachen.de:62555"},"canonical_url":"https://search.dev.ndltd.org/etd/aachen/oai:publications.rwth-aachen.de:62555","repository":{"repo_id":"aachen","name":"RWTH Aachen University","base_url":"https://publications.rwth-aachen.de/oai2d"},"display":{"title":"Untersuchungen zu uniaxial anisotropen Heisenberg-Antiferromagneten in zwei Dimensionen","abstract":"Motivated by recent experiments on cuprate antiferromagnets two-dimensional Ising and anisotropic Heisenberg models have been studied. Ising models with mobile and pinned defects are shown to describe the formation and thermal destruction of defect stripes. Modelling a specific \"telephone number compound\", a realistic Heisenberg model with randomly distributed, static defects reproduces nicely the experimental data on an anomaly in the susceptibility as a function of the external field. Moreover basic aspects of the phase diagrams of the XXZ antiferromagnet on a square lattice and variants have been analysed, using ground state considerations and Monte Carlo techniques. In particular the role of biconical structures and fluctuations in the classical version has been emphasised. For the quantum variant, the previously proposed scenario of a first-order transition between the antiferromagnetic and spin-flop phases has been scrutinised.","abstract_html":"Motivated by recent experiments on cuprate antiferromagnets two-dimensional Ising and anisotropic Heisenberg models have been studied. Ising models with mobile and pinned defects are shown to describe the formation and thermal destruction of defect stripes. Modelling a specific "telephone number compound", a realistic Heisenberg model with randomly distributed, static defects reproduces nicely the experimental data on an anomaly in the susceptibility as a function of the external field. Moreover basic aspects of the phase diagrams of the XXZ antiferromagnet on a square lattice and variants have been analysed, using ground state considerations and Monte Carlo techniques. In particular the role of biconical structures and fluctuations in the classical version has been emphasised. 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Ising models with mobile and pinned defects are shown to describe the formation and thermal destruction of defect stripes. Modelling a specific \"telephone number compound\", a realistic Heisenberg model with randomly distributed, static defects reproduces nicely the experimental data on an anomaly in the susceptibility as a function of the external field. Moreover basic aspects of the phase diagrams of the XXZ antiferromagnet on a square lattice and variants have been analysed, using ground state considerations and Monte Carlo techniques. In particular the role of biconical structures and fluctuations in the classical version has been emphasised. For the quantum variant, the previously proposed scenario of a first-order transition between the antiferromagnetic and spin-flop phases has been scrutinised."]},{"key":"dc:source","label":"Dc Source","values":["Aachen : Publikationsserver der RWTH Aachen University 121 S. : graph. Darst. (2007). = Aachen, Techn. Hochsch., Diss., 2007"]},{"key":"dc:title","label":"Title","values":["Untersuchungen zu uniaxial anisotropen Heisenberg-Antiferromagneten in zwei Dimensionen"]}]}],"canonical_facts":{"dc:contributor":["Selke, Walter"],"dc:coverage":["DE"],"dc:creator":["Holtschneider, Martin"],"dc:date":["2007"],"dc:description":["Motivated by recent experiments on cuprate antiferromagnets two-dimensional Ising and anisotropic Heisenberg models have been studied. Ising models with mobile and pinned defects are shown to describe the formation and thermal destruction of defect stripes. Modelling a specific \"telephone number compound\", a realistic Heisenberg model with randomly distributed, static defects reproduces nicely the experimental data on an anomaly in the susceptibility as a function of the external field. Moreover basic aspects of the phase diagrams of the XXZ antiferromagnet on a square lattice and variants have been analysed, using ground state considerations and Monte Carlo techniques. 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