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Title: Effect of L1{sub 2} ordering in antiferromagnetic Ir-Mn epitaxial layer on exchange bias of FePd films

Two series of samples of single-layer IrMn and IrMn/FePd bilayer films, deposited on a single-crystal MgO substrate at different IrMn deposition temperatures (T{sub s} = 300–700 °C), were investigated using magnetron sputtering. L1{sub 2} ordering was revealed for the 30 nm-thick IrMn epitaxial (001) films with T{sub s} ≥ 400 °C, determined by synchrotron radiation x-ray diffractometry (XRD). XRD results also provide evidence of the epitaxial growth of the IrMn films on MgO substrate. Increasing T{sub s} from 400 to 700 °C monotonically increases the ordering parameter of L1{sub 2} phases from 0.17 to 0.81. An in-plane exchange bias field (H{sub eb}) of 22 Oe is obtained in a 10 nm-thick FePd film that is deposited on the disordered IrMn films. As the L1{sub 2} ordering of the IrMn layers increases, the H{sub eb} gradually decreases to 0 Oe, meaning that the exchange bias behavior vanishes. The increased surface roughness, revealed by atomic force microscopy, of the epitaxial IrMn layers with increasing T{sub s} cannot be the main cause of the decrease in H{sub eb} due to the compensated surface spins regardless of the disordered and ordered (001) IrMn layers. The change of antiferromagnetic structure from the A1 to the L1{sub 2} phase was correlated with the evolution of H{sub eb}.
Authors:
;  [1] ;  [2] ;  [3] ; ; ; ; ;  [2] ;  [4] ;  [4] ;  [3] ;  [5]
  1. Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China)
  2. Department of Materials Science and Engineering, Feng Chia University, Taichung 407, Taiwan (China)
  3. (China)
  4. National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan (China)
  5. Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China)
Publication Date:
OSTI Identifier:
22410076
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; ANTIFERROMAGNETISM; ATOMIC FORCE MICROSCOPY; DEPOSITION; EPITAXY; FILMS; INTERMETALLIC COMPOUNDS; IRIDIUM; LAYERS; MAGNESIUM OXIDES; MANGANESE; MONOCRYSTALS; ROUGHNESS; SPUTTERING; SUBSTRATES; SURFACES; SYNCHROTRON RADIATION; TEMPERATURE DEPENDENCE; X-RAY DIFFRACTION