Phase transitions in magnetic clusters and other finite systems

This cumulative dissertation consists of seven articles dealing with phase transitions of magnetic clusters or other finite systems. We show that phase transitions in finite systems, which can be experimentally seen only in floppy humps of the specific heat or the magnetic susceptibility, can be quantitatively described by an analysis of an optimized estimation of the probability distribution of the system states combined with Landau free energy, or by analyzing the partition function in the complex temperature plane, or other complex-time response functions such as the complex specific heat. We show that new efficient methods, such as the Ferrenberg analysis, not applicable to infinite systems, can be applied to finite systems, even if the systems have more than one external parameter. With an Optimized Multidimensional Data Analysis of histograms produced by canonical Monte Carlo simulations, we are able to compute the phase behaviour of finite magnetic systems over a wide temperature and magnetic field range just by determining observables at a few given temperatures and magnetic fields.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Universität Oldenburg

Year

2001

Author dc:creator

• Stamerjohanns, Heinrich Wilhelm

• [Keine Schlagwörter von Autor/in vergeben.]

Repository record source_url

http://oops.uni-oldenburg.de/303

OAI identifier oai:identifier

oai:oops.uni-oldenburg.de:303