Experimental evidences of enhanced magnetocaloric properties at room temperature and half-metallicity on Fe2MnSi-based Heusler alloys

FAPERJ - FUNDAÇÃO CARLOS CHAGAS FILHO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIROFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOHeusler alloys are widely studied due to their interesting structural and magnetic properties, like magnetic shape memory ability, coupled magneto-structural phase transitions and half-metallicity; ruled, for many cases, by the valence electrons number (N-v). The present work focuses on the magnetocaloric potentials of half-metals, exploring the effect of N-v on the magnetic entropy change, preserving half-metallicity. The test bench is the Si-rich side of the half-metallic series Fe2MnSi1-xGax. From the obtained experimental results it was possible to propose vertical bar Delta S vertical bar(max) = Delta H-0.8 (alpha + beta N-v), i.e., the maximum magnetic entropy change depends in a linear fashion on N-v, weighted by a power law on the magnetic field change Delta H (alpha and beta are constants experimentally determined). This phenomenological model opens doors for further theoretical investigations. In addition, it was also possible to predict a new multifunctional Heusler alloy, with enhanced magnetocaloric effect, Curie temperature close to 300 K and half-metallicity. (C) 2016 Elsevier B.V. All rights reserved.Heusler alloys are widely studied due to their interesting structural and magnetic properties, like magnetic shape memory ability, coupled magneto-structural phase transitions and half-metallicity, ruled, for many cases, by the valence electrons number (N-v). The present work focuses on the magnetocaloric potentials of half-metals, exploring the effect of N-v on the magnetic entropy change, preserving half-metallicity. The test bench is the Si-rich side of the half-metallic series Fe2MnSi1-xGax. From the obtained experimental results it was possible to propose vertical bar Delta S vertical bar(max) = Delta H-0.8 (alpha + beta N-v), i.e., the maximum magnetic entropy change depends in a linear fashion on N-v, weighted by a power law on the magnetic field change Delta H (alpha and beta are constants experimentally determined). This phenomenological model opens doors for further theoretical investigations. In addition, it was also possible to predict a new multifunctional Heusler alloy, with enhanced magnetocaloric effect, Curie temperature close to 300 K and half-metallicity.1742327FAPERJ - FUNDAÇÃO CARLOS CHAGAS FILHO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIROFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPERJ - FUNDAÇÃO CARLOS CHAGAS FILHO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIROFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOSem informaçãoSem informaçãoSem informaçãoSem informaçãoAccess to Laboratório de Caracterização de Materiais at IF-Sudeste MG (Juiz de Fora, Brazil), Laboratório de Difração de Raios-X at IF–UFF (Niterói, Brazil) and Laboratório de Baixas Temperaturas at UNICAMP (Campinas, Brazil) are gratefully acknowledged by all authors, in which also acknowledge FAPERJ, FAPESP, CAPES, CNPq and PROPPI-UFF for financial support