Application of SQUIDs to low temperature and high magnetic field measurements—ultra low noise torque magnetometry
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Torque magnetometry is a key method to measure the magnetic anisotropy and quantum oscillations in metals. In order to resolve quantum oscillations in sub-millimeter sized samples, piezo-electric micro-cantilevers were introduced. In the case of strongly correlated metals with large Fermi surfaces and high cyclotron masses, magnetic torque resolving powers in excess of 104 are required at temperatures well below 1 K and magnetic fields beyond 10 T. Here, we present a new broadband read-out scheme for piezo-electric micro-cantilevers via Wheatstone-type resistance measurements in magnetic fields up to 15 T and temperatures down to 200 mK. By using a two-stage superconducting-quantum interference device as a null detector of a cold Wheatstone bridge, we were able to achieve a magnetic moment resolution of Δm = 4 × 10−15 J/T at maximal field and 700 mK, outperforming conventional magnetometers by at least one order of magnitude in this temperature and magnetic field range. Exemplary de Haas-van Alphen measurement of a newly grown delafossite, PdRhO2, was used to show the superior performance of our setup.
Arnold , F , Naumann , M , Lühmann , T , Mackenzie , A P & Hassinger , E 2018 , ' Application of SQUIDs to low temperature and high magnetic field measurements—ultra low noise torque magnetometry ' Review of Scientific Instruments , vol 89 , no. 2 , 023901 . DOI: 10.1063/1.5011655
Review of Scientific Instruments
© 2018, the Author(s). This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1063/1.5011655
Authors thank the Max-Planck Society and Deutsche Forschungsgemeinschaft, project “Fermi-surface topology and emergence of novel electronic states in strongly correlated electron systems,” for their financial support.
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