超导体电输运及交流磁化率双模式测量系统研制

Study for measuring high-T_c superconductor transition temperature with electric transport and AC susceptibility methods

介绍了一种基于小型制冷机的超导转变温度电输运和交流磁化率双模式单腔测量装置。该装置包括电输运法测量和交流磁化率法测量两部分,分别实现对高温超导薄膜样品的超导转变温度的测量。电输运法测量部分利用四点法测量原理对超导薄膜的电阻进行测量,获取电阻随温度变化的曲线;同时利用电流换向法消除热电势带来的测量误差,以进一步提高测量的精度。交流磁化率法测量部分利用的是电磁感应原理和超导磁效应。该部分包含有初级线圈和次级线圈,超导样品放置于两线圈之间。初级线圈用于产生交变激励磁场,次级线圈的输出信号反应了超导样品磁化率的变化,其输出信号由锁相放大器获取。测量过程中使用计算机自动记录测量数据。

This paper described a device for measuring high - Tc. superconducting transition temperature just in one chamber based on small cryoeooler with electric transport and AC susceptibility methods. The electric transport method adopted a four - wire method to eliminate the resistances of wires and the contact resistance between the leads and the sample. And during the measurement process the current reversal method was applied to eliminate the thermoelectric voltages. The AC susceptibility method adopted a lock - in amplifier to provide, an AC voltage for the primary coil and to measure the electrical signals of the see- ondary coil related with the AC susceptibility signal of the sample. The advantage of this device was that we could obtain the R - T curve and the V - T curve （ related with AC susceptibility of the sample） of a superconducting sample in the same chamber with measured datum recorded automatically by a PC computer.