Spin-glass behaviors in carrier polarity controlled Fe{sub 3−x}Ti{sub x}O{sub 4} semiconductor thin films

Journal Article · Fri Aug 14 00:00:00 EDT 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4928408· OSTI ID:22494722

Seki, M.; Adachi, M.; Takahashi, M.; Nasu, H.; Tabata, H. ^[1]; Horiba, K.; Kumigashira, H. ^[2]

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1. Department of Electrical Engineering and Information Systems, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)
2. KEK, Photon Factory, Tsukuba, Ibaraki 305-0801 (Japan)

Carrier-type control of spin-glass (cluster spin-glass) is studied in order to engineer basic magnetic semiconductor elements using the memory functions of spin-glass. A key of carrier-polarity control in magnetite is the valence engineering between Fe(II) and Fe(III) that is achieved by Ti(IV) substitution. Single phases of (001)-oriented Fe{sub 3−x}Ti{sub x}O{sub 4} thin films have been obtained on spinel MgAl{sub 2}O{sub 4} substrates by pulsed laser deposition. Thermoelectric power measurements reveal that Ti-rich films (x = 0.8) show p-type conduction, while Ti-poor films (x = 0.6–0.75) show n-type conduction. The systematic Fe(III) reduction to Fe(II) followed by Ti(IV) substitution in the octahedral sublattice is confirmed by the X-ray absorption spectra. All of the Fe{sub 3−x}Ti{sub x}O{sub 4} films (x = 0.6–0.8) exhibit ferrimagnetism above room temperature. Next, the spin-glass behaviors of Ti-rich Fe{sub 2.2}Ti{sub 0.8}O{sub 4} film are studied, since this magnetically diluted system is expected to exhibit the spin-glass behaviors. The DC magnetization and AC susceptibility measurements for the Ti-rich Fe{sub 2.2}Ti{sub 0.8}O{sub 4} film reveal the presence of the spin glass phase. Thermal- and magnetic-field-history memory effects are observed and are attributed to the long time-decay nature of remanent magnetization. The detailed analysis of the time-dependent thermoremanent magnetization reveals the presence of the cluster spin glass state.

• OSTI ID: 22494722
• Journal Information: Journal of Applied Physics, Vol. 118, Issue 6; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CARRIERS
ENERGY BEAM DEPOSITION
FERRIMAGNETISM
LASER RADIATION
MAGNETIC FIELDS
MAGNETIC SEMICONDUCTORS
MAGNETITE
MAGNETIZATION
PULSED IRRADIATION
SPIN GLASS STATE
SPINELS
TEMPERATURE RANGE 0273-0400 K
THIN FILMS
TIME DEPENDENCE
TITANIUM
TITANIUM OXIDES
VALENCE
X-RAY SPECTRA