Low temperature thermomagnetic properties of very heavy fermions suitable for adiabatic demagnetization refrigeration

TL;DR

This paper investigates the thermomagnetic properties of Yb-based intermetallics to enhance adiabatic demagnetization refrigeration at sub-Kelvin temperatures, proposing criteria for selecting optimal materials based on entropy trajectories.

Contribution

It introduces new thermodynamic analysis of Yb compounds for low-temperature refrigeration and proposes simple relationships to compare magnetocaloric behavior for different applications.

Findings

Different entropy trajectories identified depending on specific heat at low temperatures.

Proposed criteria aid in selecting suitable materials for specific refrigeration applications.

Comparison with CMN salt highlights advantages of new materials.

Abstract

With the aim of improving the performance of classical paramagnetic salts for adiabatic refrigeration processes at the sub-Kelvin range, relevant thermodynamic parameters of some new Yb-based intermetallic compounds are analyzed and compared. Two alternative potential applications are recognized, like those requiring fixed temperature reference points to be reached applying low intensity magnetic fields and those requiring controlled thermal drift for temperature dependent studies. Different thermomagnetic entropy S(T,B) trajectories were identified depending on respective specific heat behaviors at very low temperature. To gain insight into the criteria to be used for a proper choice of suitable materials in respective applications, some simple relationships are proposed to facilitate a comparative description of their magnetocaloric behavior, including the referent Cerium-Magnesium-Nitride (CMN) salt in these comparisons