Design of opposed-anvil-type high-pressure cell for precision magnetometry and its application to quantum magnetism

TL;DR

This paper presents a highly sensitive opposed-anvil high-pressure cell for magnetometry, capable of detecting minute susceptibilities under ultrahigh pressures, with applications to quantum magnetism.

Contribution

The authors designed a nearly zero magnetic response high-pressure cell and developed background subtraction procedures, enabling precise measurement of tiny sample magnetism at high pressures.

Findings

Achieved detection of susceptibilities as small as 10^{-4}

Enhanced space efficiency with conical gasket and cupped anvils

Successfully measured paramagnetic susceptibilities under high pressure

Abstract

We have developed a much sensitve technique to conduct magnetometry under ultrahigh pressures up to 6.3~GPa, which can detect a weak volume susceptibilities as small as $\sim 10^{-4}$. An opposed-anvil-type high-pressure cell is designed by numerical analysis to give nearly zero magnetic response, in a commercial SQUID magnetometer. We introduced procedures for subtracting background contributions from a high-pressure cell by taking displacements of the cell parts into account, and found a way of resolving tiny magnetism of a sample from given magnetometer response curves. A non-magnetic material, binderless tungsten carbide ceramic, is employed. To increase sample-signal-to-background ratio further, a conical shaped gasket and cupped anvils are introduced, yielding nearly ten times better space efficiency. The new set-up and analysis are applied to measure the paramagnetic susceptibilities of spin orbit entangled moment under pressures.