AC Heat capacity and magnetocaloric effect measurements for pulsed magnetic fields

TL;DR

This paper introduces a new calorimeter for measuring AC heat capacity and magnetocaloric effect in small samples under pulsed magnetic fields down to 2 K, demonstrating its performance with specific magnetic materials.

Contribution

The paper presents a novel calorimeter design capable of precise measurements in high pulsed magnetic fields, with detailed calibration and testing on specific magnetic compounds.

Findings

Calorimeter achieves b1 1mK temperature precision at 2 K.

Effective thermometry using calibrated RuO2 thermometers.

Successful measurement of heat capacity and magnetocaloric effect in tested materials.

Abstract

A new calorimeter for measurements of the AC heat capacity and magnetocaloric effect of small samples in pulsed magnetic fields is discussed for the exploration of thermal and thermodynamic properties at temperatures down to 2 K. We tested the method up to \mu 0H = 50 Tesla, but it could be extended to higher fields. For these measurements we used carefully calibrated bare chip Cernox\textregistered and RuO2 thermometers, and we present a comparison of their performance. The monotonic temperature and magnetic field dependences of the magneto resistance of RuO2 allow us to carry on precise thermometry with a precision as good as \pm 1mK at T = 2 K. To test the performance of our calorimeter, AC heat capacity and magnetocaloric effect for the spin-dimer compound Sr3Cr2O8 and the triangular lattice antiferromagnet RbFe(MoO4)2 are presented.