Electromechanical magnetization measurements at ultralow temperatures and high magnetic fields

A new magnetization measurement system, which is designed to be used in ultralow temperatures and high magnetic fields, has been developed. In this equipment, a small capacitor is used and its capacitance changes by the displacement of an electrode due to force acting on a magnetic material placed on the electrode. The most significant point of this equipment is that a Ni plate is placed just below the capacitor to make a gradient field at the sample position instead of usual field-gradient coils installed in a magnet. Using this system, we have studied precise magnetization measurements on rare-earth monopnictides Ce0.9La0.1Sb and a uranium heavy Fermion superconductor UPd2Al3 at temperature down to 0.5 K in high magnetic fields provided by a superconducting magnet and a hybrid magnet.