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dc.contributor.author林志忠en_US
dc.contributor.authorLIN JUHN-JONGen_US
dc.date.accessioned2014-12-13T10:47:49Z-
dc.date.available2014-12-13T10:47:49Z-
dc.date.issued2009en_US
dc.identifier.govdocNSC97-2112-M009-017-MY2zh_TW
dc.identifier.urihttp://hdl.handle.net/11536/101126-
dc.identifier.urihttps://www.grb.gov.tw/search/planDetail?id=1747619&docId=297654en_US
dc.description.abstract本计画拟研究四个介观与奈米尺寸以及无序系统的基础物理课题:(一)拟探讨无序系统中的dynamical structural defects(或兩能级隧穿系统two-level tunneling systems)。我们计画寻找适当的材料样品,研究兩能级隧穿系统与导电电子耦合从而造成的低温传输性质。兩能级隧穿系统常常造成類似(非磁性)近藤效应的物理现象,同时也可能造成电子相位相干时间的破坏,是凝态物理学中的一个极基础而重要的多体物理课题。(二)拟研究金属/绝缘体/金属隧道结的低温穿隧电流现象。在nano-granular金属隧道结中,无序的影响会使得费米能级处的电子能态密度降低,因而造成微分电导(differential conductance或dI/dV)在零偏压处有一个很明显的极小值。但是当有(磁性或轨道)近藤效应存在时,零偏压处的微分电导反而会有一个极大值。我们将在低温下以及高磁场中进行测量,以深入研究产生极小或极大值微分电导的微观物理机制;尤其将探讨后者由近藤效应产生的dI/dV对温度以及偏压的scaling行为。(三)拟持续介观系统中电子相位相干时间的量测,将继续研究无序系统中的电子—声子散射与电子—声子—杂质干涉现象,探讨该项干涉在介观及奈米样品中产生的新电、热效应,并厘清退相干(dephasing)机制。(四)拟进行单根金属及半导体奈米线的低温电性与量子传输特性之量测,和新物理现象或非费米液行为之探索。
兩能级隧穿系统和电子退相干机制的研究往往需要在极低温下和极高磁场中进行,为了进行超低温的量测,本计画拟加强与日本理化学研究所(RIKEN)的“低温物理实验室”的国际合作,使用其超大型3He-4He稀释制冷机,以期得到最确切而无疑意的數据。同时开展交大—RIKEN—东京大学三方在垂直双量子点之自旋依赖传输课题的合作研究。本计画也将加强与理論学家的密切讨論与合作。
zh_TW
dc.description.abstractIn this program, we propose to study several very fundamental physics topics in mesoscopic and nanoscale structures as well as in disordered systems. (1) We propose to investigate the effects of dynamical structural defects (i.e., defects with internal degrees of freedom) on the electronic transport in disordered samples. The transport behavior due to interactions between conduction electrons and dynamic defects (often modeled as two-level tunneling systems) will be investigated. The roles of dynamic defects in governing the electron dephasing time at very low temperatures will be studied. (2) We will measure the differential conductances of metal/insulator/metal tunnel junctions. The suppression of electronic density of states at the Fermi level in disordered nano-granular metals, which results in profound zero bias conductance dips, will be studied. In addition, we will study the important case of tunnel junctions which show zero-bias conductance peaks. Such conductance peaks may arise from an enhanced tunneling current due to magnetic or orbital Kondo effect. The scaling behavior of dI/dV with temperature and bias voltage will be explored at low temperatures and in high magnetic fields. (3) We plan to continue our measurements of electron dephasing time at ultra-low temperatures to clarify the issue of whether the dephasing time near the absolute zero temperature should diverge or saturate to a finite value. The electron-phonon scattering time in the dirty limit as well as the electron-phonon-impurity interference effect in disordered metals will also be pursued. (4) We plan to carry out electrical measurements on individual metal as well as semiconductor nanowires to investigate the fundamental electrical transport properties, bearing in mind to search for possible evidence of non-Fermi liquid states in nanostructures.
In order to clarify the roles of dynamical structural defects and to measure the electron dephasing time at ultra-low temperatures and in high magnetic fields, we propose to further strengthen our ongoing international collaborations with Dr. Kimitoshi Kono, Chief Scientist of the Low Temperature Physics Laboratory at RIKEN, Japan. Dr. Kono’s Laboratory is equipped with several high-cooling-power 3He-4He dilution refrigerators, and is one of the most prestigious low temperature physics laboratories in the world. We will also initiate a “NCTU-RIKEN-Tokyo” collaborative project on spin-dependent transport in vertical double quantum dots. We shall establish close collaborations with theorists to understand the underlying physics of our experimental results.
en_US
dc.description.sponsorship行政院国家科学委员会zh_TW
dc.language.isozh_TWen_US
dc.title介观及奈米尺寸结构中电子动力学及相互作用之研究 (II)zh_TW
dc.titleElectron Dynamics and Interactions in Mesoscopic and Nanoscale Structures (II)en_US
dc.typePlanen_US
dc.contributor.department国立交通大学物理研究所zh_TW
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