Fabrication of (Fe,Zn)3O4 -BiFeO3
nano-pillar structure by self-assembled growth
Tanaka LaboratoryTakuya Sakamoto
Contents
• Research background(spintronics)
• Functional oxides in 1-dimensional structure• Nano-pillar structure• Self-assembled method• My research
• Summary and future plan
Research background (spintronics)
e-charge
spin
Spin and charge
Electronics
spintronicsspintronics
Magnetics
e- e- e- e- e- e- e-
E
田中秀和等 , 機能材料 28 54 (2008)
Ferromagnetic semiconductorMagnetism depends on carrier concentration
ferroelectricsSponteneos electric polarization
Modulation of magnetism by electric field
(Fe,Zn)3O4/Pb(Zr,Ti)O3
Functional oxide is attractive !!Functional oxide is attractive !!
AFM
FM
Functional oxides in 1-dimensional structure
M. Fäth, et.al, Science 285 1540 (1999)
domain
FMAFM
Average properties in 2-dimensional structure
Single domain properties in 1-dimensional structure
(La,Ca)MnO3
Yanagisawa et.al, Appl.Phys.Lett 89 253121 (2006)
100nm
Nano-pillar structureNano-pillar structure
Average properties in 2-dimensional structure
Single domain properties in 1-dimensional structure
Self-assembled method
Mixed state
Limitation of size
Limitation of size
Phase separation
Self –assembly growth using difference of wetting condition
Top down method
Self-assembled method
perovskitespinel
spinel
Haimei Zheng et.al, Nano.Lett 6 1401(2006)
Wetting condition
perovskite
My research• (1) fabrication of nano-pillar structure target : (BiFeO3)0.65(Fe2.2Zn0.8O4)0.35
PLD装置 (ArF excimer laser) substrate : SrTiO3(100)
substrate temperature : 400℃ ~ 700 ℃ Oxygen pressure : 0.01Pa ~ 10Pa
• (2) crystal structure x-ray diffraction (θ-2θ)
• (3) surface structure Atomic Force Microscope (AFM) Scanning Electron Microscope (SEM)
Ferromagnetic semiconductorferroelectrics
Result 1 (crystal structure)
10 20 30 40 50 60
101
102
103
104
105
2θ
(100)(200)
(400)FZO
BFO
BFO
STO STO(100) (200)
Optimized deposition condition
BFO = BiFeO3
STO = SrTiO3
FZO = (Fe2.2Zn0.8O4)
Both epitaxial FZO and BFO could be grown on STO by self-assembly method.
Result2 (surface structure)
2 μm
(Fe,Zn)3O4
BiFeO3
Surface SEM image cross section SEM image
EPMA(Electron Probe Micro Analyzer)
Nano-pillar structure was obtained
Surface AFM image
500 nm
InterfaceSTO
FZOBFO
Summary• Nano-pillar structure was obtained by self-assembled
method
Future plan• Nanopillar structure by self-assembly growth has possibility to
control single domain properties and to enhance the efficiency of magnetism modulation.
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