测量超导转换温度的数据采集系统

本文介绍电感法测量超导转换温度时采用的计算机数据采集系统.该系统主机采用国产小型机NS-131机.除模数(A/D)转换器外,其余部分均系国产组件组装而成. 所谓电感法是基于迈斯纳效应,在正常和超导两态的转换中,样品中磁通将产生很大的变化.如果将样品置于LC组成的振荡回路的电感线圈中,超导转换时样品磁通的变化必然引起线圈电感量的变化,进而引起振荡器振荡频率 产生变化,因此可用测定频率来确定超导体的转换温度Tc.一般取Tc=(T1+T2)/2,T1,T2分别是频率改变10%和90%时的相应温度值. 有人曾分别用数字电压表和频率计来观察、记录标准温…     

超导重力仪的研制

本文介绍了Goodkind型超导重力仪的研制,并用它观察到了地球固体潮汐。     

串联DC-SQUID阵列的实验研究

本文研究了高温超导３×３并联ＤＣＳＱＵＩＤ串联阵列台阶约瑟夫森结。其性能指标：７７Ｋ下,磁通白噪声为８．９×１０－５Φ０／Ｈｚ,磁场灵敏度在白噪声段为２×１０－１１Ｔ／Ｈｚ．研究表明,约瑟夫森结的并联对衬底台阶晶界结离散性较大的器件参量有很好的补偿作用     

PREPARATION OF a-AXIS ORIENTED YBa2Cu3Ox THIN FILMS

The a-axis oriented YBa₂Cu₃O_x(YBCO) thin films could be grown on (100) SrTiO₃(STO) substrates with STO buffer layers by dc and rf magnetron sputtering either by low-ering the deposition temperature, or by using a self-template technique. For the latter, the resistivity of the thin film at 290K along the substrate [001] direction is about four times larger than that in the [010] direction. The zero resistance temperatures T_c0 are 89 K in both directions. So high quality a-axis oriented YBCO thin films can be prepared by the self-template technique. Also the T_c0 increase monotonously with the reduction of the thickness of the YBCO seed layer.     

铊膜DC－SQUID磁强计的噪声测量

ＤＣ－ＳＱＵＩＤｓ由铊膜制备．用两种方法测量了闭环ＤＣ－ＳＱＵＩＤ磁强计的噪声．研究了环境噪声对磁强计噪声测量的影响．     

TI膜微桥隧道结的低频1／f噪声

我们在７７Ｋ下测量了ＴＩ膜微桥结的低频１／ｆ电压噪声和Ｉ－Ｖ特性曲线并得到了１０ＨＺ下偏置电流和电压噪声关系．实验结果表明在临界电流附近总有噪声峰出现．在不同的磁场下冷却样品，噪声峰的幅度并不改变．这一结果意味着ＴＩ膜微桥隧道结的１／ｆ噪声主要来自于临界电流的涨落，而不象是由于磁通捕获造成的．     

PREPARATION OF a-AXIS ORIENTED YBa2Cu3Ox THIN FILMS

The a-axis oriented YBa₂Cu₃O_x(YBCO) thin films could be grown on (100) SrTiO₃(STO) substrates with STO buffer layers by dc and rf magnetron sputtering either by low-ering the deposition temperature, or by using a self-template technique. For the latter, the resistivity of the thin film at 290K along the substrate [001] direction is about four times larger than that in the [010] direction. The zero resistance temperatures T_c0 are 89 K in both directions. So high quality a-axis oriented YBCO thin films can be prepared by the self-template technique. Also the T_c0 increase monotonously with the reduction of the thickness of the YBCO seed layer.