Magnetic and magnetotransport properties of Zn{sub x}Fe{sub 3−x}O{sub 4−y} thin films
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7588, INSP, 4 Place Jussieu, F-75005 Paris (France)
- National Institute for Lasers, Plasma and Radiation Physics, L22 P.O. Box MG-36, 77125 Bucharest (Romania)
- Univ. Orleans, UMR CNRS 7344, GREMI, 14 Rue Issoudun, F-45067 Orleans 2 (France)
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 by 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.
- OSTI ID:
- 22402722
- Journal Information:
- Journal of Applied Physics, Vol. 116, Issue 21; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
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