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Title: Epitaxial Ni-Mn-Ga-Co thin films on PMN-PT substrates for multicaloric applications

Multicaloric stacks consisting of a magnetocaloric film on a piezoelectric substrate promise improved caloric properties as the transition temperature can be controlled by both magnetic and electric fields. We present epitaxially grown magnetocaloric Ni-Mn-Ga-Co thin films on ferroelectric Pb(Mg{sub 1/3}Nb{sub 2/3}){sub 0.72}Ti{sub 0.28}O{sub 3} substrates. Structure and microstructure of two samples, being in the austenitic and martensitic state at room temperature, are investigated by X-ray diffraction in two- and four-circle geometry and by atomic force microscopy. In addition, high temperature magnetometry was performed on the latter sample. The combination of these methods allows separating the influence of epitaxial growth and martensitic transformation. A preferential alignment of twin boundaries is observed already in the as-deposited state, which indicates the presence of prestress, without applying an electric field to the substrate. A temperature-magnetic field phase diagram is presented, which demonstrates the inverse magnetocaloric effect of the epitaxial Ni-Mn-Ga-Co film.
Authors:
; ; ;  [1] ;  [2] ; ;  [1]
  1. IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany)
  2. (Germany)
Publication Date:
OSTI Identifier:
22494686
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 5; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ATOMIC FORCE MICROSCOPY; AUSTENITIC STEELS; ELECTRIC FIELDS; EPITAXY; FERROELECTRIC MATERIALS; MAGNETIC FIELDS; MAGNETIC PROPERTIES; MARTENSITIC STEELS; MICROSTRUCTURE; PHASE DIAGRAMS; PHASE TRANSFORMATIONS; PIEZOELECTRICITY; SUBSTRATES; TEMPERATURE RANGE 0273-0400 K; TEMPERATURE RANGE 0400-1000 K; THIN FILMS; TRANSITION TEMPERATURE; X-RAY DIFFRACTION