Paradoxical magnetic cooling in a structural transition model

Is contrast to the experimentally widely used isentropic demagnetization pr ocess for cooling to ultra-low temperatures we examine a particular classic al model system that does not cool, but rather heats up with isentropic dem agnetization. This system consists of several magnetite particles in a coll oidal suspension, and shows the uncommon behavior of disordering structural ly while ordering magnetically in an increasing magnetic field. For a six-p article system, we report an uncommon structural transition from a ring to a chain as a function of magnetic field and temperature.