Broadband microwave spectroscopy in Corbino geometry at 3He temperatures

Steinberg, Katrin; Scheffler, Marc; Dressel, Martin

doi:10.1063/1.3680576

Cited by 22 publications

(23 citation statements)

References 20 publications

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“…For thicker or thinner films different geometries are possible [82]. The specimen is cooled down to 1.1 K and even lower temperatures are available [83]. Figure 9(a) shows data (taken at different frequencies on a film with thickness 500Å and a room temperature resistivity of 8.7 ⋅ 10 −5 Ω cm) of the temperature dependence of the real part of the conductivity.…”

Section: Resultsmentioning

confidence: 99%

Electrodynamics of Metallic Superconductors

Dressel

2013

Advances in Condensed Matter Physics

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The theoretical and experimental aspects of the microwave, terahertz, and infrared properties of superconductors are discussed. Electrodynamics can provide information about the superconducting condensate as well as about the quasiparticles. The aim is to understand the frequency dependence of the complex conductivity, the change with temperature and time, and its dependence on material parameters. We confine ourselves to conventional metallic superconductors, in particular, Nb and related nitrides and review the seminal papers but also highlight latest developments and recent experimental achievements. The possibility to produce well-defined thin films of metallic superconductors that can be tuned in their properties allows the exploration of fundamental issues, such as the superconductor-insulator transition; furthermore it provides the basis for the development of novel and advanced applications, for instance, superconducting single-photon detectors.

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Section: Resultsmentioning

confidence: 99%

Electrodynamics of Metallic Superconductors

Dressel

2013

Advances in Condensed Matter Physics

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“…Additionally a 30dB broadband microwave amplifier ranging from 0.5 to 18 GHz was implemented at the second port of the NWA. 63 The 4 He glass cryostat of this setup combined with a rotary and a roots pump allows temperatures at the sample lower than 1.1 K. 13,51 The mounting for the resonator box holds a temperature sensor and a heater to control temperature. Before the actual measurement, a broadband spectrum is taken at 7.5 K, slightly above the T c of the lead resonator, whose phase will later serve in calibration purposes.…”

Section: Measurement Setupmentioning

confidence: 99%

“…Finally, the compact design of the probe can easily be implemented into a dilution refrigerator, opening a route toward microwave studies on bulk metals and superconductors at temperatures well below 1 K, a temperature range that has rarely been explored for microwave spectroscopy on conducting materials so far. 15,19,23,34,51 …”

Section: Introductionmentioning

confidence: 99%

Surface-resistance measurements using superconducting stripline resonators

Hafner

Dressel

Scheffler

2014

Review of Scientific Instruments

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We present a method to measure the absolute surface resistance of conductive samples at a set of GHz frequencies with superconducting lead stripline resonators at temperatures 1 -6 K. The stripline structure can easily be applied for bulk samples and allows direct calculation of the surface resistance without the requirement of additional calibration measurements or sample reference points. We further describe a correction method to reduce experimental background on high-Q resonance modes by exploiting TEM-properties of the external cabling. We then show applications of this method to the reference materials gold, tantalum, and tin, which include the anomalous skin effect and conventional superconductivity. Furthermore, we extract the complex optical conductivity for an all-lead stripline resonator to find a coherence peak and the superconducting gap of lead.

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“…16 In this article, we describe the design of our microwave spectrometer to measure the complex conductance of thin films of InO x 17,18 and graphene 19 at 3 He temperatures and high magnetic fields. Related measurements at 3 He temperatures have also been reported by the Stuttgart group 20 where they have set up a broadband Corbino spectrometer in the temperature range from 450 mK to 2 K. However, no magnetic field dependence measurements have been reported from their group in this temperature range. In our group, the spectrometer covers the frequency range between 0.05 GHz and 16 GHz down to 300 mK and at magnetic fields up to 8 T. We demonstrate that we can repeat the measurements in a very reliable fashion over the interesting temperature and field ranges.…”

Section: Introductionmentioning

confidence: 89%

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

Liu

Pan

Armitage

2014

Review of Scientific Instruments

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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.

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Broadband microwave spectroscopy in Corbino geometry at 3He temperatures

Cited by 22 publications

References 20 publications

Electrodynamics of Metallic Superconductors

Electrodynamics of Metallic Superconductors

Surface-resistance measurements using superconducting stripline resonators

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

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