Ultra-low-temperature Vector-magnet Magnetic-force Microscope

We have built a He magnetic force microscope (MFM), operating at a base temperature of 300 mK with a vector field of Z 9 T, X 2 T, Y 2 T for the three axes, respectively. Our microscope has a capability of scanning multiple samples in a single cooldown. Together with the comparative Meissner technique, this capability allows measurements of the magnetic penetration depth as a function of the doping level, which is important for understanding the nature of the purported quantum critical point within a superconductor dome in high-Tc, pnictides and heavy-fermion superconductors. Here, we show applications of our novel microscope to investigate unconventional magnetic materials and magnetic superconductors after it had been built at IBS-POSTECH in 2014.