Study of elementary charge excitation in strongly correlated materials by shot noise measurment

通过散粒噪声测量研究强相关材料中的基元电荷激发

基本信息

批准号：
14340101
负责人：
MAEDA Atsutaka
金额：
$ 9.28万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

(1)Construction of PLD apparatus : A capability of the thin film synthesis using Pulsed laser deposition technique was constructed. In the very beginning, we had problems in the homogeneity of films because of the insufficient substrate temperature. So, we improved the apparatus by changing the method of raising the substrate temperature. By this improvement, we succeeded in making films with good superconductivity properties.(2)Synthesis of thin film samples : Using the above mentioned apparatus, we prepared La-Sr-CuO cuprate superconductors with various hole concentrations for a broad range in the phase diagram. As a result of resistivity measurement on these films, we confirmed that phase diagram of temperature vs carrier concentration of our films agreed well with that already reported in bulk single crystals.(3)Study of wet etching of high-Tc cuprate sample : We tried to make narrow wires by the wet etching techniques, by using various different kinds of chemical solutions. Unfort … More unately, however, all the results were unsuccessful.(4)Study of making narrow wires by FIB technique : We tried to make narrow wires by the focused ion beam (FIB) lithography technique. Unfortunately, however, we did not succeeded in making nano-scale wires applicable in the shot noise experiment.(5)Study of development of electrical contacts with ultra-low contact resistance : We did not get good results for this either. We strongly feel that a circumstance where all the capability of FIB, OLD and those for electrical measurements are located at the same place is indispensable for the success of shot noise measurement in oxide superconductors.(6)Investigation of phase diagram of high-Tc cuprate superconductor by superconductivity fluctuation measurement with ac conductivity measurement (broadband technique) : Although we have not succeeded in obtaining good results for shot noise measurement, we measured ac conductivity of synthesized films by broadband technique developed by our selves, where microwave frequency can be varied in a continuous manner. In all the underdoped samples, the superconductivity fluctuation and superconductivity transition can be understood completely in terms of two dimensional XY model. On the other hand, for optimally doped crystals, it changes in the three dimensional XY model. Our preliminary results show that the overdoped samples show two dimensional behavior again, suggesting that the optimally doped sample is very special in the phase diagram. This may be related to a possible existence of quantum critical point at an almost optimally doped hole concentration. Less

（1）构建PLD设备：使用脉冲激光沉积技术的薄膜合成能力。一开始，由于底物温度不足，我们在膜的均匀性方面遇到了问题。因此，我们通过更改提高底物温度的方法来改善设备。通过这种改进，我们成功地制作了具有良好超导性特性的膜。（2）薄膜样品的合成：使用上述设备，我们准备了La-Sr-Cuo Cuprate超导体，具有各种孔浓度，以在相图中范围广泛。由于对这些膜的耐药性测量结果，我们证实了温度与膜的载体浓度的相位图与已经在散装单晶中已经报道的相一致。（3）研究高-TC Cuprate样品的湿蚀刻的研究：我们试图通过使用各种不同种类的化学化学溶液来制造湿蚀刻技术的狭窄电线。不幸的是……更不合理的是，所有结果都没有成功。（4）通过FIB技术制作狭窄的电线的研究：我们试图通过聚焦离子束（FIB）光刻技术来制造狭窄的电线。但是，不幸的是，我们没有成功地制造出适用于Shot Noise实验中的纳米级线。（5）研究具有超低接触电阻的电气接触的开发：我们也没有为此获得良好的结果。我们强烈认为，在氧化物超导体中，在氧化物超导体中取得成功的较高的fib，旧和电气测量能力的情况是必不可少的。测量，我们通过自我开发的宽带技术测量了合成膜的交流电导率，在该技术可以连续变化微波频率。在所有被压倒性的样品中，可以完全理解超导性波动和超导性转变，以二维XY模型来理解。另一方面，对于最佳掺杂晶体，它在三维XY模型中发生变化。我们的初步结果表明，超额样品再次显示了二维行为，这表明最佳掺杂样品在相图中非常特别。这可能与几乎最佳掺杂孔浓度处的量子临界点可能存在有关。较少的