The magnetocaloric behavior of LaCaMn1−xFexO3 for x = 0.00, 0.02, 0.03, 0.05, 0.07, 0.08 and 0.10 under the influence of an external magnetic field was simulated and analyzed. Simulations were carried out using the Monte Carlo method and the classical Heisenberg model under the Metropolis algorithm. These mixed valence manganites are characterized by having three types of magnetic ions corresponding to , which are bonded with , and and , related to . The ions were randomly included, replacing ions. With this model, the magnetic entropy change, , in an isothermal process was determined. showed maximum peaks around the paramagnetic-ferromagnetic transition temperature, which depends on doping. Relative cooling power was computed for different concentrations varying the magnetic applied field. Our model and results show that the doping decreases the magnetocaloric effect in the LaCaMn1−xFexO3, making this a bad candidate for magnetic refrigeration. The strong dependence of the magnetocaloric behavior on doping and the external magnetic field in LaCaMn1−xFexO3 can boost these materials for the future technological applications.
The manganites have been widely studied because of their important properties as colossal magnetoresistance and exchange bias that are important phenomena used in many technological applications. For this reason, in this work, a study of the exchange bias effect present in La2/3Ca1/3MnO3/La1/3Ca2/3MnO3. This study was carried out by using the Monte Carlo method and the Metropolis Algorithm. In order to make easy this study, a graphic user interface was built alloying a friendly interaction. The interface permits to control the thickness of Ferromagnetic and Antiferromagnetic layer, temperatures the magnetic field, the number of Monte Carlo steps and the exchange parameters. Results obtained reflected the influence of all of these parameters on the exchange bias and coercive fields.
KeywordsBilayers, exchange bias, graphic interface, manganites.
ResumenLas manganitas han sido ampliamente estudiadas debido a sus propiedades importantes tales como magnetorresistencia colosal y polarización de intercambio, que son fenómenos importantes empleados en diversas aplicaciones tecnológicas. Por esta razón, en este trabajo se presenta el estudio del efecto de la polarización de intercambio (exchange bias) para el caso de bicapas de La2/3Ca1/3MnO3/La1/3Ca2/3MnO3. Este estudio se llevó a cabo empleando el método de Monte Carlo junto con el algoritmo de Metropolis. Con el fin de que este estudio sea más fácil, se construyó una interface gráfica para hacer más amigable la interacción con el usuario. La interface permite el control de parámetros como el espesor de la película, la temperatura, el campo magnético el número de pasos de Monte Carlo y los parámetros de intercambio. Los resultados obtenidos reflejaron la influencia de todos estos paráme-tros sobre el Exchange bias y el campo coercitivo.
Palabras claveBicapas, polarización de Intercambio, interfaz gráfica, manganitas.Revista Tecno Lógicas No. 26, Junio de 2011 [135]
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