Application of SQUIDs to low temperature and high magnetic field measurements - Ultra low noise torque magnetometry

Abstract

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 $10^4$ are required at temperatures well below $1\mathrm{K}$ and magnetic fields beyond $10\mathrm{T}$. Here, we present a new broadband read-out scheme for piezo-electric micro-cantilevers via Wheatstone-type resistance measurements in magnetic fields up to $15\mathrm{T}$ and temperatures down to $100\mathrm{mK}$. By using a two-stage SQUID as null detector of a cold Wheatstone bridge, we were able to achieve a magnetic moment resolution of $\Delta m=5\times 10^{-15}J/T$ at maximal field, outperforming conventional magnetometers by at least two orders of magnitude in this temperature and magnetic field range. Exemplary de Haas-van Alphen measurement of a newly grown delafossite, PdRhO${}_2$, were used to show the superior performance of our setup.

References in corpus (6)

• Heavy Fermions and Quantum Phase Transitions
• High Temperature Superconductivity in Iron Pnictides and Chalcogenides
• The properties of ultrapure delafossite metals
• Quantum oscillations and high carrier mobility in the delafossite PdCoO${}_2$
• Current Sensing Noise Thermometry: A fast practical solution to low temperature measurement
• Quasi two-dimensional Fermi surface topography of the delafossite PdRhO${}_2$

Cited by in corpus (3)

• Resonant torsion magnetometry in anisotropic quantum materials
• The Fermi surface of PtCoO2 from quantum oscillations and electronic structure calculations
• Quantum oscillation studies of the nodal line semimetal Ni3In2S2-xSex