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A Monte Carlo study of Ferrimagnetic Heisenberg models
2008 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The aim of this work was to investigate, through Monte Carlo simulations, three different lattices on the anisotropic Heisenberg model and check their correctness in terms of ferrimagnetic and critical behaviour. In the first model, a layered simple cubic structure with two magnetic sublattices, conditions for the existence of a compensation point was established. The second and third model were set up to resemble the real substances, with known material parameters, of yttrium iron garnet (YIG) and gadolinium iron garnet (GdIG). Those materials have a rather complicated crystal structure with two and three magnetic sublattices, respectively. The first model shows the same characteristic ferrimagnetic behaviour as a two sublattice geometry of this kind should. The remaining two models are in good agreement to experimental data. For the YIG lattice no compensation point exists, as should be the case, and the critical temperature falls within 96% accuracy (T=520°K). The same simulations for the GdIG model give a compensation point at T=360°K (compared to the experimental value of T=288°K) and a critical point of T=565°K (compared to T=564°K). One obvious conclusion from this is that the method of Monte Carlo is an effective technique to study these kinds of magnetic structures. This work was performed on the Department of Theoretical Physics at the University of New South Wales (UNSW) in Sydney, Australia, with supervision from Prof. Jaan Oitmaa.

Place, publisher, year, edition, pages
Keyword [en]
Physics Chemistry Maths, Monte Carlo, Garnet, Heisenberg model, YIG, GdIG, Yttrium, iron garnet, Gadolinium iron garnet, Y3Fe5O12, Gd3Fe5O12
Keyword [sv]
Fysik, Kemi, Matematik
URN: urn:nbn:se:ltu:diva-58820ISRN: LTU-EX--08/054--SELocal ID: f626eed7-f44e-4353-90c2-34204ea5f88dOAI: diva2:1032208
Subject / course
Student thesis, at least 30 credits
Educational program
Engineering Physics, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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