Precise magnetization measurements under high pressures in the diamond-anvil cell

A precise magnetization measurement system for extremely small samples in the diamond-anvil cell has been developed. The system is based on position differentiating detection (PDD) combined with the use of a SQUID magnetometer. The PDD is a kind of vibrating coil magnetometer and is suitable for the case where high sensitivity detection is required for a sample around which there is little space for the detection coil. The present system enables one to make magnetization measurements at pressures up to about 12 GPa in the temperature range from 1.4 to 30 K. The sensitivity is about 10−9–10−10 emu. Three piezoelectric actuators of a bimorph type are used at liquid–helium temperature for stable vibration of the detection coil with an amplitude of 90 μm around the tips of the diamond anvils. The design and construction of the system is described in detail. The performance of the system is illustrated by magnetization measurements of EuTe under high pressures.