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Title: Increased magnetic moment induced by lattice expansion from α-Fe to α′-Fe{sub 8}N

Buffer-free and epitaxial α-Fe and α′-Fe{sub 8}N{sub x} thin films have been grown by RF magnetron sputtering onto MgO (100) substrates. The film thicknesses were determined with high accuracy by evaluating the Kiessig fringes of X-ray reflectometry measurements allowing a precise volume estimation. A gradual increase of the nitrogen content in the plasma led to an expansion of the iron bcc unit cell along the [001] direction resulting finally in a tetragonal distortion of about 10% corresponding to the formation of α′-Fe{sub 8}N. The α-Fe lattice expansion was accompanied by an increase in magnetic moment to 2.61 ± 0.06μ{sub B} per Fe atom and a considerable increase in anisotropy. These experiments show that—without requiring any additional ordering of the nitrogen atoms—the lattice expansion of α-Fe itself is the origin of the increased magnetic moment in α′-Fe{sub 8}N.
Authors:
; ;  [1] ;  [1] ;  [2]
  1. Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany)
  2. (Germany)
Publication Date:
OSTI Identifier:
22402982
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANISOTROPY; BCC LATTICES; EPITAXY; EXPANSION; IRON; IRON NITRIDES; MAGNESIUM OXIDES; MAGNETIC MOMENTS; NITROGEN; SPUTTERING; SUBSTRATES; THIN FILMS