1. Fabrication of (Fe,Zn) 3 O 4 -BiFeO 3 nano-pillar structure by self- assembled growth Tanaka Laboratory Takuya Sakamoto

2. Contents Research background(spintronics) Functional oxides in 1-dimensional structure Nano-pillar structure Self-assembled method My research Summary and future plan

3. Research background (spintronics) e-e- charge spin Spin and charge Electronics spintronics Magnetics e-e- e-e- e-e- e-e- e-e- e-e- e-e- Ｅ 田中秀和等, 機能材料 28 54 (2008) Ferromagnetic semiconductor Magnetism depends on carrier concentration ferroelectrics Sponteneos electric polarization Modulation of magnetism by electric field (Fe,Zn) 3 O 4 /Pb(Zr,Ti)O 3 Functional oxide is attractive !!

4. AFM FM Functional oxides in 1-dimensional structure M. Fäth, et.al, Science 285 1540 (1999) domain FM AFM Average properties in 2-dimensional structure Single domain properties in 1-dimensional structure (La,Ca)MnO 3 Yanagisawa et.al, Appl.Phys.Lett 89 253121 (2006) 100nm

5. Nano-pillar structure Average properties in 2-dimensional structure Single domain properties in 1-dimensional structure

6. Self-assembled method Mixed state Limitation of size Phase separation Self –assembly growth using difference of wetting condition Top down method Self-assembled method perovskitespinel Haimei Zheng et.al, Nano.Lett 6 1401(2006) Wetting condition perovskite

7. My research （１） fabrication of nano-pillar structure target ： (BiFeO 3 ) 0.65 (Fe 2.2 Zn 0.8 O 4 ) 0.35 ＰＬＤ装置 (ArF excimer laser) substrate ： SrTiO 3 (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

8. Result 1 (crystal structure) 2θ (100) (200) (400) ＦＺ Ｏ ＢＦ Ｏ STO (100)(200) Optimized deposition condition ＢＦＯ = BiFeO 3 STO = SrTiO 3 ＦＺＯ = (Fe 2.2 Zn 0.8 O 4 ) Both epitaxial FZO and BFO could be grown on STO by self-assembly method.

9. Result2 (surface structure) ２ μm (Fe,Zn) 3 O 4 BiFeO 3 Surface SEM imagecross section SEM image EPMA(Electron Probe Micro Analyzer) Nano-pillar structure was obtained Surface AFM image 500 nm Interface STO FZO BFO

10. 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.