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DY: Fachverband Dynamik und Statistische Physik

DY 28: Phase transitions and Critical Phenomena II

DY 28.4: Vortrag

Donnerstag, 25. März 2010, 15:00–15:15, H47

Microcanonical phase diagrams of short-range ferromagnets — •Michael Kastner¹ and Michel Pleimling² — ¹National Institute for Theoretical Physics, Stellenbosch 7600, South Africa — ²Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0435, USA

A phase diagram is a graph in parameter space showing the phase boundaries of a many-particle system. Commonly, the control parameters are chosen to be those of the (generalized) canonical ensemble, such as temperature and magnetic field. However, depending on the physical situation of interest, the (generalized) microcanonical ensemble may be more appropriate, with the corresponding control parameters being energy and magnetization. We show that the phase diagram on this parameter space looks remarkably different from the canonical one. The general features of such a microcanonical phase diagram are investigated by studying two models of ferromagnets with short-range interactions. The physical consequences of the findings are discussed, including possible applications to nuclear fragmentation, adatoms on surfaces, and cold atoms in optical lattices.