abstract
Full Heusler alloys are well known to either crystallize in a cubic structure (Cu2MnAl-type), or present tetragonal distortions. Both structure types present interesting properties, like room temperature magnetic memory shape effect and/or remarkable magnetocaloric effect, mainly ruled by strong magnetostructural coupling. Due to this interplay, our aim was to produce a new crystal phase for the Heusler alloys, different from those well-established cubic and tetragonal, responsible for those well-known physical properties. Thus, we have produced nanoparticles of full Heusler alloys using a pulsed laser deposition technique (from targets of Fe2MnSi) and obtained a core-shell pattern, presenting an amorphous shell and a crystalline core, with hexagonal symmetry. In accordance with these experimental findings, it was shown, by means of density functional calculation, the existence of a minimum of energy as a function of the hexagonal lattice parameters, with a true indication that the hexagonal phase is metastable. The magnetic properties differ considerably from those of bulk Fe2MnSi, including an increase of the Curie temperature from 220 K to 295 K, which is of potential interest for room-temperature applications. This work opens the door to research in a new family of materials, whose properties have only now begun to be explored. (C) 2018 Elsevier Ltd. All rights reserved.
keywords
SENSITIZED SOLAR-CELLS; MATERIALS SCIENCE; PHOTOANODE
subject category
Materials Science
authors
Checca, NR; Caraballo-Vivas, RJ; Coelho, AA; Rossi, A; Fortunato, NM; Mohseni, F; Goncalves, JN; Amaral, JS; Rocco, DL; Reis, MS
our authors
Farzin Mohseni
PhD Student
João Cunha de Sequeira Amaral
Assistant Researcher
João Nuno Santos Gonçalves
Junior Researcher
Nuno Fortunato
Research FellowshipGroups
G2 - Photonic, Electronic and Magnetic Materials
G6 - Virtual Materials and Artificial Intelligence
Projects
CICECO - Aveiro Institute of Materials (UID/CTM/50011/2013)
Projeto de Investigação Exploratória: João Amaral (IF/01089/2015)
acknowledgements
MSR acknowledges FAPERJ, CAPES and CNPq (Brazil) for funding the research projects. 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, POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. This work was also funded by FEDER funds through the COMPETE 2020 Programme and National Funds through 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.