Properties of the 100 kHz Quartz Tuning Forks in Strong Magnetic Fields and Very Low Temperatures
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Properties of the 100 kHz Quartz Tuning Forks in Strong Magnetic Fields and Very Low Temperatures ˇ Marcel Cloveˇ cko1 · Peter Skyba1 Received: 16 July 2019 / Accepted: 19 November 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2019
Abstract We present the properties of the standard, commercial 100 kHz quartz tuning forks at very low temperatures and high magnetic fields up to 8 Tesla. We show that the resonance frequency of the tuning forks depends weakly on the strength of magnetic field. This makes the quartz tuning forks a promising low-temperature thermometer having the B/T ratio up to 1000. We discuss the physical origin of the observed experimental results. Keywords Quartz tuning fork · Strong magnetic field · Thermometry
1 Introduction Over the last decade, quartz tuning forks have become important experimental tools in the field of low-temperature physics used mainly to study quantum liquids and solids, quantum turbulence, etc. [1–10]. Furthermore, tuning forks play important role in scanning probe techniques such as AFM and STM [11–13] as well. The latter measurements are usually performed in vacuum at low temperatures and in strong magnetic fields. It is therefore essential to know the influence of strong magnetic field on the resonant characteristics of quartz tuning fork in vacuum. Our previous work clearly showed the independence of the tuning fork constant on the applied magnetic field [14]. In this article, we present preliminary results of experimental measurements using commercially available 100 kHz tuning fork in temperature range below 1 K down to 20 mK and in magnetic fields up to 7.5 Tesla.
B 1
Peter Skyba [email protected] Centre of Low Temperature Physics, Institute of Experimental Physics, SAS and P. J. Šafárik University Košice, Watsonova 47, 04001 Kosice, Slovakia
123
Journal of Low Temperature Physics
2 Experimental Details Before installation, the 100 kHz tuning fork was adopted for measurements in high magnetic field: Its original metal can has been removed and former (magnetic) leads were replaced by the copper wires having a diameter of 120 µm. These copper wires were electrically connected to tuning fork’s pads using a conductive silver epoxy and glued to a small piece of Stycast 1266-epoxy impregnated paper in order to achieve a mechanical stiffness of the setup. Subsequently, the copper wires were insulated by means of fishing lines. Assembled fork’s setup was put in copper cylindrical can and glued using Stycast 1266 epoxy resin. A screw thread ending the copper can served for its mechanical connection to a silver plate which was placed in the center of the superconducting magnet. In order to achieve effective cooling, the silver plate was connected to the mixing chamber of the cryo-free dilution refrigerator Triton 200 using three silver rods of the diameter of 4 mm. Additional cooling of the tuning forks was ensured by clamping their copper wires between two copper blocks screwed to the mixing chamber plate. In order to measure quartz tuning fork wit
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