Experimental realisation of off-stoichiometric Fe-Mn-Si full Heusler alloy with hexagonal crystal structure by pulsed laser deposition

authors	Checca, NR; Caraballo-Vivas, RJ; Coelho, AA; Rossi, A; Fortunato, NM; Mohseni, F; Goncalves, JN; Amaral, JS; Rocco, DL; Reis, MS
nationality	International
journal	MATERIALS & DESIGN
author keywords	Nanoparticles; Pulsed laser deposition; Heusler alloys; Structural change
keywords	SENSITIZED SOLAR-CELLS; MATERIALS SCIENCE; PHOTOANODE
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.
publisher	ELSEVIER SCI LTD
issn	0264-1275
year published	2018
volume	143
beginning page	268
ending page	273
digital object identifier (doi)	10.1016/j.matdes.2018.01.062
web of science category	Materials Science, Multidisciplinary
subject category	Materials Science
unique article identifier	WOS:000425879300029