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.