Establishment of the Reproducibility of the Superconducting Gap in Tunneling measurements.

隧道测量中超导间隙再现性的建立。

基本信息

批准号：
08640436
负责人：
KUNII Satoru
金额：
$ 1.22万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08640436/
关键词：
Superconductor Superconducting-gap Tunneling effect Point-contact

项目摘要

The purpose of this research project is to establish the reproducibility of superconducting gap value in the point-contact tunneling spectroscopy. In the superconductor the Andreev-reflection changes depend on the contact size (correlated to the phase coherence) so as to arise the excess current and the subharmonic gap structure. In this study it is tried to change the contact size and to cancel the vector-unbalance with the phase of the detected signal. For this aim the two-phase output oscillator is used to remove the circuit unbalane voltage and the unbalance signal phase. The equipment for the point-contact tunneling measurements was constructed to prevent the contamination and the needle-pressure by the automatic in situ cleaning method developed by us. The superconductor single crystal YB_6 was grown by a vertical floating zone method by an author. The measurements were performed to get the differential resistivity as a function of the bias-voltage at very low temperature. It is possible to change the phase of 0.1 degree in the two phase output oscillator independently. The precise variable resistor was used to get voltage-balance so far instead of the two phase output oscillator. Therefore it was difficult to control the phase relation in the circuit so as to arise the non-reproducible signal or the ghost signal. By this research project the unbalance of the voltage and the phase are removed simultaneously, so that the distinction between the signal from the sample and the signal from the circuit is achieved.

该研究项目的目的是确定在点接触隧道光谱中超导间隙值的可重复性。在超导体中，Andreev反射的变化取决于接触大小（与相干性相关），以便出现多余的电流和亚谐波间隙结构。在这项研究中，它试图改变接触大小，并通过检测到的信号取消矢量不平衡。为此，使用两相输出振荡器来卸下电路不义电压和不平衡信号相。构建了点接触隧道测量的设备，以防止我们开发的自动原位清洁方法的污染和针线。超导体单晶YB_6是由作者通过垂直浮动区方法生长的。进行测量以在非常低的温度下获得差异电阻率作为偏置电压的函数。可以独立改变两个相输出振荡器中0.1度的相位。到目前为止，精确的可变电阻器用于获得电压平衡，而不是两个相输出振荡器。因此，很难控制电路中的相位关系，以便出现不可复制的信号或幽灵信号。通过该研究项目，电压和相位的不平衡同时删除，以便实现来自样品的信号与电路信号之间的区别。