(Tri)critical Phase Transitions in Magnetocaloric Materials
Much of today's research in so-called functional materials is driven by the quest for technologies that use energy more efficiently and reduce our impact on the environment. Such pressures drive a renewed investigation of some of the most fundamental properties of condensed matter. Solid-state phase transitions are one good example. In order to find an energy efficient solution to the problem of reducing our use of HFCs in a variety of cooling applications, a new field has been defined.
In "ferroic cooling", a good solid refrigerant has a phase transition with a large entropy change, tuned by chemical composition over the temperature range of the particular application . I will show how the search for suitable magnetic refrigerants leads to: a survey of novel critical and tricritical material systems [2,3], the development of characterization tools to study first order phase transitions, and hi-resolution neutron diffraction data that act as an ideal test of ab initio theories of finite temperature magnetism .
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