Electronic and bulk magnetic property characterization of i-QC and AC samples at ambient and high pressures

Research group: Peter Lazor, Roland Mathieu and Andreas Rydh.

To extract the potentially unique properties of i-QCs, it is important to compare their physical properties to those of rational approximants of the same intermetallic system. Furthermore, the explicit characterization of properties requires ultrapure single grain QCs and single crystalline ACs – as afforded from melt-growth processes.

Magnetic susceptibility and magnetization will be measured at ambient pressure and under pressure with miniature DACs mounted in the cryostat of the PPMS. Recently several designs of miniature DACs, made of nonmagnetic high strength materials, have been reported that can be conveniently interfaced with the sample rod of the MPMS. In this project we will exploit and further develop those designs, to achieve pressures in excess of 10 GPa. (Magneto) resistance and Hall effect will be measured on a PPMS system .

Sub-Kelvin temperatures, which are necessary for systematic studies into quantum criticality, cannot be reached with the cryostats of MPMS and PPMS systems. Instead, a dilution refrigerator with space for a DAC will be employed. We identify heat capacity as a key property for p-T and B-p-T phase diagram studies into quantum criticality. Heat capacity measurements will be based on nanocalorimetry which combines high resolution with the possibility to measure small and ultrapure sample specimens. A major development project is to enable nanocalorimetry at high pressure conditions. We plan to adapt our calorimeter system to make it compatible with a DAC, targeting a unique pressure range of 0 – 30 GPa. This set-up will represent our workhorse for quantum criticality studies.