resumo
Half-metallic compounds present two spin bands with contrasting behaviors, resulting in 100% of spin polarization at the Fermi level; property of crucial importance for applications in spintronic devices. Materials presenting this characteristic are, for instance, some Heusler compounds, mainly Co-2-based compounds, which have interesting properties, such as T-C above 1000 K and high values of saturation magnetization. However, atomic disorder can affect the half-metallic properties of these materials, decreasing their potential application in spintronic devices. Our aim is to evaluate the role played by atomic disorder in Co2FeSi, which has a Curie temperature of 1100 K and saturation magnetization close to 6 mu(B). In order to experimentally probe the effects of atomic disorder in this material, samples were subjected to different annealing times, with a subsequent quantification of the disorder degree by means of anomalous X-ray diffraction (AXRD) and Mossbauer spectroscopy. In addition, DFT calculations were performed to provide information on the density of states (DoS) at the Fermi energy under those disorder conditions. This work reveals how disorder plays an important role on the thermodynamic and electronic properties of half-metallic Heusler compounds.
palavras-chave
RAY-POWDER DIFFRACTION; ELECTRONIC-STRUCTURE; MAGNETIC-PROPERTIES; XRD1 BEAMLINE; MAGNETORESISTANCE; SPINTRONICS; ORDER
categoria
Chemistry; Materials Science; Metallurgy & Metallurgical Engineering
autores
Caraballo-Vivas, RJ; Tedesco, JCG; Checca, NR; Fortunato, NM; Goncalves, JN; Sanchez, DR; Carvalho, AMG; Amaral, JS; Reis, MS
nossos autores
João Cunha de Sequeira Amaral
Investigador Auxiliar
João Nuno Santos Gonçalves
Investigador Júnior
Nuno Fortunato
Bolseiro de investigaçãoProjectos
CICECO - Aveiro Institute of Materials (UID/CTM/50011/2019)
Projeto de Investigação Exploratória: João Amaral (IF/01089/2015)
agradecimentos
We acknowledge FAPERJ, FAPESP, CAPES, CNPq, and PROPPI-UFF for financial support. MSR belongs to the INCT of Refrigeracao e Termofisica, funding by CNPq by grant number 465448/2014-3. This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, FCT Ref. UID/CTM/50011/2019, financed by national funds through the FCT/MCTES. This work is also funded by FEDER funds through the COMPETE 2020 Programme and National Funds throught FCT - Portuguese Foundation for Science and Technology under the project UID/CTM/50025/2013. JNG and JSA acknowledge FCT grants SFRH/BPD/82059/2011 and IF/01089/2015, respectively. This study was financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior - Brasil (CAPES) - Finance Code 001.