一台在³He温度和高磁场条件下的宽带微波科贝诺光谱仪。

A broadband microwave Corbino spectrometer at ³He temperatures and high magnetic fields.

作者信息

Liu Wei, Pan LiDong, Armitage N P

机构信息

Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA.

出版信息

Rev Sci Instrum. 2014 Sep;85(9):093108. doi: 10.1063/1.4895798.

DOI:10.1063/1.4895798

PMID:25273708

Abstract

We present the technical details of a broadband microwave spectrometer for measuring the complex conductance of thin films covering the range from 50 MHz up to 16 GHz in the temperature range 300 mK-6 K and at applied magnetic fields up to 8 T. We measure the complex reflection from a sample terminating a coaxial transmission line and calibrate the signals with three standards with known reflection coefficients. Thermal isolation of the heat load from the inner conductor is accomplished by including a section of NbTi superconducting cable (transition temperature around 8-9 K) and hermetic seal glass bead adapters. This enables us to stabilize the base temperature of the sample stage at 300 mK. However, the inclusion of this superconducting cable complicates the calibration procedure. We document the effects of the superconducting cable on our calibration procedure and the effects of applied magnetic fields and how we control the temperature with great repeatability for each measurement. We have successfully extracted reliable data in this frequency, temperature, and field range for thin superconducting films and highly resistive graphene samples.

摘要

我们介绍了一种宽带微波光谱仪的技术细节，该光谱仪用于测量温度范围在300 mK至6 K、外加磁场高达8 T时，覆盖50 MHz至16 GHz范围的薄膜的复电导。我们测量终止同轴传输线的样品的复反射，并使用具有已知反射系数的三种标准对信号进行校准。通过包含一段NbTi超导电缆（转变温度约为8 - 9 K）和气密密封玻璃珠适配器，实现了热负载与内导体的热隔离。这使我们能够将样品台的基础温度稳定在300 mK。然而，这种超导电缆的加入使校准过程变得复杂。我们记录了超导电缆对校准过程的影响、外加磁场的影响以及我们如何在每次测量中以高度可重复性控制温度。我们已经成功地在这个频率、温度和磁场范围内提取了薄超导薄膜和高电阻石墨烯样品的可靠数据。