Study of the magnetocaloric effect in nanostructured manganite films

The saving and consumption of energy in modern society depends to a large extent on easily accessible cooling. cooling without the use of conventional gas compression and expansion technology represents a challenge for the future of this field. in this sense, much of the interest is placed on the advantages offered by refrigeration based on solid devices; which involves efficient systems, low cost and more environmentally friendly technologies. magnetic refrigeration is based on the study of the magnetocaloric effect (mce), which consists of the thermal changes that a material undergoes, produced by an applied magnetic field. the current research of the mce, is oriented, both in understanding the microscopic mechanisms that govern it,as in the search for new materials that present high thermal response to moderate values ??of magnetic fields. in particular, mixed valence oxides known as manganites, allow to generate a wide variety of compounds with different magnetic properties, including the magnetocaloric effect. the manganites are characterized by the general formula r1-xmxmno3, where r can be a trivalent rare earth atom and m a alkaline earth divalent. depending on the value of x in the doping, these materials present a varied magnetic and transport phase diagram. in the metallic ferromagnetic fm state, particularly near the critical curie temperatures, tc, and metal-insulator transition, tmi; is where phenomena such as colossal magnetoresistance, cmr (resistance can be drastically reduced,when an external magnetic field is applied), whose theoretical explanation has not yet been fully established.

Study the magnetocaloric effect in thin films of la2 / 3ca1 / 3mno3 (lcmo) manganite, both pure and doped; as a potential application in magnetic refrigeration.

With this project it is expected to establish a study of the magnetocaloric effect (mce) in complex mixed valence magnetic oxides (manganites), and relate it to the critical behavior around the magnetic transition. the method applied in this study allows to reliably calculate critical parameters in inhomogeneous materials. in addition to obtaining the optimum conditions to manufacture powder system (or block) and in the form of thin films of lcmo and lcmfo using the sputtering technique - sputtering with dc magnetron, on different monocrystalline substrates, it is expected to establish a comparison of the effects of the substrate in the behavior of the magnetic transitions for each of the compounds, and relate these results with the thermal properties. an expected result,is the contribution in the development of new materials, studying alternative systems as possible candidates in the technological application of magnetic refrigeration. the final results will be published in journals of the isi-scopus international databases, and the disclosure will be made in at least one international or one national event.