Torque Differential Magnetometry Using Qplus-mode of Quartz Tuning Fork

Quartz tuning fork is the key component of high-resolution atomic force microscope. Because of its high quality factor, quartz tuning fork can also be used for high sensitivity magnetometry. Herein, we developed a highly sensitive torque differential magnetometry using the Qplus-mode of a quartz tuning forks. The tuning fork is driven by an AC voltage and its deflection is measured by the resultant AC current. We observed a sharp resonance of the quartz tuning fork at low temperature down to 1.6 K. We calibrated our torque differential magnetometry by measuring the angular dependence of the hysteresis loop in single crystalline Fe0.25TaS2. Furthermore, we demonstrated the high sensitivity of the torque differential magnetometry by measuring the quantum oscillations of bismuth single crystal. The extracted Fermi surface cross sections are consistent with those of bismuth crystals.