2008 Annual Report Vol.36 - 中研院物理研究所 - Academia Sinica

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• We have observed several interesting quantum-size effects on the magnetisim and superconductivity in nanomaterials of heavy fermion systems. • We have developed the new methods for the production of high quality magnetic/superconducting nanoparticles and thin films • We have developed a new wide-range low temperature sensor for calorimeter application using transition metal oxides. • We have observed the coexistence of magnetic order and superconductivity in Ru-based double perovskite oxides. Major research achievements: • The evolution of Kondo interactions and magnetic correlation with size variation and Core (magnetic)- shell (nonmagnetic) model in CePt 2 The evolution of the Kondo effect and antiferromagnetic correlations with size reduction in CePt 2 nanoparticles (3.1-26 nm) is studied by analysis of the temperature-dependent specific heat and magnetic susceptibility. The antiferromagnetic correlations diminish with size reduction. The Kondo effect predominates at small particle size with trivalent, small Kondo temperature magnetic regions coexisting with strongly mixed valent, large T K nonmagnetic regions. From the data of specific heat of bulk and nanoparticles, the integrated entropy S M =∫(C M /T)dT is close to 100 % of Rln2 for bulk CePt 2 , however we find n M =0.86, 0.69 and 0.25 for d = 26, 22 and 3.1 nm, respectively. The distribution configuration of magnetic and nonmagnetic Ce ions can be sketched by a core (magnetic)- shell (nonmagnetic) model (Phys. Rev. Lett, 98, 157206, 2007). • Room temepature ferromagnetism in capped CdSe nanocrystals We demonstrated the synthesis of nanocrystals of a nominally non magnetic semiconductor that exhibit ferromagnetism at several degrees above room temperature. The nanocrystals are capped by TOPO (Tri-n-octylphosphine) which is also nonmagnetic. The RTFM arises from electronic effects at the crystal surfaces due to the presence of the TOPO. The importance of the work is that with appropriate surface modification, i.e., capping with TOPO for our case, the semiconductor quantum dots exhibit RTFM with no need of magnetic dopants. The work was published in advanced materials and also selected by Nature Publishing Group (NPG) Asia Materials website for the best research published in the Asia-Pacific region. (Advanced Materials, 20, 1656-1660, <strong>2008</strong>). • Electrical and thermal transport in single nickel nanowire The thermal conductivity and electrical resistivity of a single suspended nickel nanowire have been measured in the temperature range 15- 300 K by means of the 18
“self heating 3ω” technique. The nanowire with dimentions 100 nm x 180 nm x 35 μm was fabricated through e-beam lithography and etching process. The temperature dependence of the thermal conductivity and the Lorenz number strongly differ from that for the bulk. The comparison of the transports in the Ni nanowire shows, that at temperatures 75 < T < 300 K Wiedemann-Franz (WF) law holds, whereas at temperatures T < 75 K the WF law is violated, indicating that thermal current in this material is suppressed more than electrical current. The results are explained by combined effect of confined dimension, enhanced disorder and grown contribution of N-processes. The figure of the paper was selected as the cover image and has been downloaded over 1000 times within a year (Appl. Phys. Lett. 92, (<strong>2008</strong>) 063101) Fig. The scanning electron microscope (SEM) image of the Ni-NW with dimensions 100 nm×180 nm×35 μm, the Ni-NW was suspended above a groove on a Si/ Si 3 N 4 substrate. III. Spintronics, magnetic nanostructures and magnetotransport physics • Magnetic nanostructures: Two methods have been used to prepare Ge nanostructures, nanosphere lithography and inert gas condensation. First, Ge nanostructures were prepared by thermally evaporating pure Ge material to deposit different thick Ge layers (from 1 to 20 nm) on top of polystyrene nanospheres with different sizes (from 20 to 500 nm), as shown in fig. 1. The size of Ge nanostructures was influenced by both the thickness of Ge layers and the size of nanospheres. The measured magnetization was inversely dependent on the thickness of Ge layers and the size of nanospheres, as shown in fig. 2. Second, Ge nanoparticles were prepared by collecting nanoparticles from a liquid nitrogen cooled cooper plate in an inert gas atmosphere (He pressure from 0.001 to 1 Torr). Nano-sized amorphous Ge nanoparticles with sizes of about 2 – 20 nm have been 19
Page 1 and 2: 中央研究院物理研究
Page 3 and 4: 中央研究院物理研究
Page 5 and 6: I Members of the Institute
Page 7 and 8: 黃英碩研究員 / 表面
Page 9 and 10: 李尚凡副研究員 / 奈
Page 11 and 12: 朱明禮研究技師 / 高
Page 13 and 14: Adjunct Faculty 姚永德 Yeong-D
Page 15 and 16: Amalendu Sau ( 邵馬度 ) Sing-L
Page 17 and 18: II Review of Research Projects
Page 19 and 20: The Institute of Physics Logo The l
Page 21 and 22: • We have reported an in situ met
Page 23: linear displacement and two-dimensi
Page 27 and 28: • We have established a Point-Con
Page 29 and 30: DNA was bombarded using a focused e
Page 31 and 32: induced charges in the silicon wire
Page 33 and 34: Superconducting/Ferromagnetic nanos
Page 35 and 36: Yung Liou Associate Research Fellow
Page 37 and 38: Intermediate and High Energy Physic
Page 39 and 40: III. Particle Physics Experimental
Page 41 and 42: channel silicon micro-strip detecto
Page 43 and 44: Suen Hou Associate Research Fellow
Page 45 and 46: Yueh-Chung Yu Associate Research Fe
Page 47 and 48: View of the Environmental Wind Tunn
Page 49 and 50: Schematic phase diagram for the int
Page 51 and 52: categorized into three classes -- c
Page 53 and 54: Wen-Tau Juan Assistant Research Fel
Page 55 and 56: III List of Ongoing Research Projec
Page 57 and 58: 主持人計劃名稱執行
Page 63 and 64: IV Publication List of 2008
Page 65 and 66: Chang, Wen-Chen( 章文箴 ) 1. K
Page 67 and 68: y resonant soft x-ray magnetic scat
Page 69 and 70: 7. Inclusive Search for Squark and
Page 71 and 72: Fermilab-Pub-08-302-E. arXiv:0808.2
Page 73 and 74: 54. Limits on the Production of Nar
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2. C. L. Chen, C. L. Dong, S. M. Ra
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14. CDF Collab., T.~Aaltonen et al.
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preparation. 3. Study of $B\to \Lam
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Jen, S. U.( 任盛源 ) 1. S. U.
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9. S. Y. Huang, J. J. Liang, S. Y.
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Lin, Shin-Ted( 林興德 ) 1. “
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Lu, Chi-Ken( 陸紀亙 ) 1. Chi-K
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21. Forward-Backward Asymmetry in T
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44. Measurement of Correlated bb-ba
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2. "Production and Decay of the Ge7
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10. Search for New Physics in the m
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3. Top Quark Mass Measurement in th
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26. Measurement of the Inclusive Je
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50. Search for Hadronic Decays of W
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detector”, H.M. Chang et al., J.
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noncentrosymmetric superconductors
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Attendance in International Confere
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會議名稱會議期間舉
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Seminars 中央研究院物
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演講題目演講者所屬
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Visiting Scholars 中央研究
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訪問學人所屬機構訪
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訪問學人所屬機構訪
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2008 Annual Report Vol.36 - 中研院物理研究所 - Academia Sinica

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