THE MEISSNER EFFECT IN TaSe_3

TaSe_3 中的迈斯纳效应

基本信息

批准号：
62540222
负责人：
NAGATA Shoichi
金额：
$ 1.41万
依托单位：
Muroran Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1989
项目状态：
已结题

项目摘要

THE MEISSNER EFFECT IN TaSe_3 The Meissner effect of the quasi-one-dimensional conductor TaSe_3 is studied using a SQUID magnetometer. Susceptibility x does not show any significant variation of diamagnetism, with magnetic fields parallel and perpendicular to crystalline b-axis over a low magnetic field range of 7.2 mOe to 4.0 Oe. The diamagnetism is quite weak and the value of chi is much less than -3.OX10^<-3> emu/cm^3. Furthermore, thd susceptibility chi does not exhibit any indication of an abrupt change at 2.1 K. A single whisker consists of many fibers where some fibers (very thin filament-like) become superconducting below 2.1 K.Resistivity of TaSe_3 drops near zero below 2.1 K. Why is the Meissner effect suppressed quite strongly in TaSe_3 ? A basic origin of this small diamagnetism is discussed on the basis of numerical computer calculations for the London model.As a simplified model, the diamagnetic susceptibility chi for a infinite cylinder having radius, a , is calculated systematically as a function of a/lambda, here lambda is the London penetration depth. In TaSe_3, the superconducting region is strictly restricted to extremely thin filaments along the b-axis in the single whisker. Furthermore. these superconducting filaments are individually isolated above 0.40 K in the whisker. The radii of the filaments are much less than lambda ( at most a/lambda <less than or equal>0.30 ), then, the magnetic flux will penetrate uniformly.Consequently the Meissner effect is substantially smeared out.It should be noted that our experimental results give the single whisker's intrinsic material property. Our results could totally differ from that of the large amount of massive specimens which are randomly oriented and are greatly interpenetrating.

tase_3中的meissner效应使用鱿鱼磁力计研究了准二维导体tase_3的meissner效应。敏感性X没有显示出磁性磁性的任何显着变化，磁场在7.2 MOE至4.0 OE的低磁场范围内平行且垂直于晶体B轴。 diamagnetism非常弱，CHI的价值远小于-3.ox10^<-3> emu/cm^3。此外，THD敏感性CHI没有表现出2.1 K处突然变化的任何迹象。单个晶须由许多纤维组成，其中一些纤维（非常薄的细丝）在2.1 K以下的超导中变得超导，Tase_3的抗性tase_3滴在2.1 k的零下2.1 K.为什么在2.1 k中。根据伦敦模型的数值计算机计算，讨论了这种小型磁性的基本起源。作为一种简化的模型，对于具有半径为半径的无限圆柱体的DiMagnetic易感性CHI被系统地计算为A/Lambda的函数，在这里，Lambda是伦敦的渗透深度。在Tase_3中，超导区域严格仅限于单晶须沿B轴极细的细丝。此外。这些超导丝在晶须中单独隔离0.40 k。细丝的半径远小于lambda（最多a/lambda <小于或等于> 0.30），然后，磁通量将均匀地穿透。导致Meissner效应基本上被涂抹了。应该指出的是，我们的实验结果给出了单Whisker的内在材料。我们的结果可能与大量大量标本的结果完全不同，这些标本是随机定向并大大互穿的。