Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 29: Poster Session: Cryogenic Particle Detectors and Cyotechnique

TT 29.17: Poster

Montag, 12. März 2018, 15:00–19:00, Poster B

VSM as top loading probe for variable-temperature inserts — •Alfons Schuck, Jörg Franke, and Michael Huth — Institute of Physics, Goethe University, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany

Although long since established as a versatile and highly sensitive method for magnetic sample characterization [1], vibrating sample magnetometry (VSM) under cryogenic conditions is still mostly an expensive add-on option for selected commercial cryo-systems [2]. Here we present a novel solution that is highly affordable and combines a standard variable-temperature insert (VTI) and a resonant-drive VSM to a ``do-it-yourself'' top loading probe. The magnetometer uses a voice-coil drive in a resonator setup at about 40 Hz eigenfrequency close to optimal damping conditions. The peak-to-peak oscillation amplitude can be set in a range from 0.1 mm to 6 mm. Time-resolved monitoring of the gradiometer coil signal is done with a common lock-in-amplifier and allows to accurately centering the probe using a linear actuator to compensate thermal expansion. The sample oscillation amplitude is continuously monitored employing an optical quadrature encoder. Details of the VSM design are presented as well as results of first test and calibration measurements. A comparison to the specifications of selected commercial VSM setups is performed.

[1] Foner, Review of Scientific Instruments 27, 548 (1956)

[2] see, e.g., Quantum Design Model P525, https://www.qdusa.com/sitedocs/appNotes/vsmappnote_5-09.pdf