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Title: Magnetic and magnetotransport properties of Zn{sub x}Fe{sub 3−x}O{sub 4−y} thin films

We present a detailed magnetic and magnetotransport investigation of spinel zinc ferrite Zn{sub x}Fe{sub 3−x}O{sub 4−y} (0.1 ≤ x ≤ 0.6) thin films grown by pulsed laser deposition on various substrates. The films are ranging from polycrystalline to (001)- or (111)-oriented. It is shown associating magnetic and resistivity measurements to x-ray and ion beam scattering analyses that the magnetic and electrical properties are tightly linked to the chemical composition and crystallinity/microstructure of the films, as they result from the choice of substrate and growth conditions. The use of oxidizing conditions (O{sub 2} pressure ≈ 10{sup −4}–10{sup −2} mbar) is highly detrimental to the crystalline quality and thus to the ferromagnetism. On the contrary, a partial O{sub 2} pressure of 3 × 10{sup −7} mbar combined to a growth temperature of 500 °C allows obtaining Zn{sub x}Fe{sub 3−x}O{sub 4−y} films displaying very good ferromagnetic features. The SiO{sub 2}/Si substrates, promoting (111) growth without interfacial effects, lead to better film properties than Al{sub 2}O{sub 3}(0001), MgO(001), or SrTiO{sub 3}(001) substrates: higher Curie temperatures and higher magnetization values (≈490 kAm{sup −1}) at room temperature. Above a Verwey-type critical temperature, a thermally activated spin polarized charge transport is observed, while in the low temperature range, the resistivity is well described bymore » the variable range hopping model. However, the negative magnetoresistance response at low field remains modest and a monotonous decrease with increasing magnetic field is observed. We show that a steeper low field magnetoresistance decrease may be obtained in polycrystalline stoichiometric layers formed by a specific two-step growth process, which significantly reduces the density of grain/antiphase boundaries.« less
Authors:
; ;  [1] ;  [2] ;  [3] ;  [4]
  1. Sorbonne Universités, UPMC Univ Paris 06, UMR 7588, INSP, 4 Place Jussieu, F-75005 Paris (France)
  2. (France)
  3. National Institute for Lasers, Plasma and Radiation Physics, L22 P.O. Box MG-36, 77125 Bucharest (Romania)
  4. Univ. Orleans, UMR CNRS 7344, GREMI, 14 Rue Issoudun, F-45067 Orleans 2 (France)
Publication Date:
OSTI Identifier:
22402722
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 21; Other Information: (c) 2014 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; ALUMINIUM OXIDES; CRITICAL TEMPERATURE; CURIE POINT; ENERGY BEAM DEPOSITION; FERRITES; LASER RADIATION; MAGNESIUM OXIDES; MAGNETIZATION; MAGNETORESISTANCE; MICROSTRUCTURE; POLYCRYSTALS; PULSED IRRADIATION; SILICON OXIDES; SPIN ORIENTATION; STRONTIUM TITANATES; SUBSTRATES; THIN FILMS; X RADIATION