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Anuncio de Seminario
Lunes 1 de Diciembre, a las 12:30
Facultad de Física
Departamento de Física de la Materia Condensada
Seminario de la 2ª planta

Making the most of the magnetic and lattice entropies
Prof. Vitalij K. Pecharsky

Ames Laboratory and Department of Materials Science and Engineering Iowa State University Ames, IA 50011-3020

The discovery of the giant magnetocaloric effect in Gd5Si2Ge2 and other R5T4 compounds (R = rare earth metal and T is a Group 14 element) generated a broad interest in the magnetocaloric effect and magnetostructural transitions.  Reports on the giant magnetocaloric effect in other systems soon followed.  These include MnFePxAs1-x and related compounds, La(Fe1-xSix)13 and their hydrides, Mn(AsxSb1-x), CoMnSixGe1-x, Ni2MnGa and some closely related Heusler phases, and several representatives of the colossal magnetoresistive manganites family.  A common feature is the enhancement of the magnetic entropy effect by the overlapping contribution from the lattice, regardless whether it is a massive structural change like in R5T4 compounds, or only a phase volume change as in La(Fe1-xSix)13.  Both the magnetic and lattice entropies are, therefore, important and each contribution must be maximized in order to have the optimum magnetocaloric effect.  Both of these entropy terms and the potential pathways towards a further enhancement of the giant magnetocaloric effect will be discussed.