Paradoxical magnetic cooling in a structural transition model
Department of Physics, Carl von Ossietzky University, 26111 Oldenburg, Germany
2 Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-1116, USA
Corresponding author: a firstname.lastname@example.org
Published online: 15 January 2001
In contrast to the experimentally widely used isentropic demagnetization process for cooling to ultra-low temperatures we examine a particular classical model system that does not cool, but rather heats up with isentropic demagnetization. This system consists of several magnetite particles in a colloidal suspension, and shows the uncommon behavior of disordering structurally while ordering magnetically in an increasing magnetic field. For a six-particle system, we report an uncommon structural transition from a ring to a chain as a function of magnetic field and temperature.
PACS: 05.70.Fh – Phase transitions: general studies / 75.10.-b – General theory and models of magnetic ordering / 75.50.Mm – Magnetic liquids
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2001