Second harmonic AC calorimetry technique within a diamond anvil cell

Abstract

Tuning the energy density of matter at high pressures gives rise to exotic and often unprecedented properties, e.g., structural transitions, insulator-metal transitions, valence fluctuations, topological order, and the emergence of superconductivity. The study of specific heat has long been used to characterize these kinds of transitions, but their application to the diamond anvil cell (DAC) environment has proved challenging. Limited work has been done on the measurement of specific heat within DACs, in part due to the difficult experimental setup. To this end we have developed a novel method for the measurement of specific heat within a DAC that is independent of the DAC design and therefore readily compatible with any DACs already performing high pressure resistance measurements. As a proof-of-concept, specific heat measurements of the MgB2 superconductor were performed, showing a clear anomaly at the transition temperature (Tc), indicative of bulk superconductivity. This technique allows for specific heat measurements at higher pressure than previously possible.

arXiv comment5 pages with 5 figures

References in corpus (8)

• Superconductivity at 250 K in lanthanum hydride under high pressures
• Evidence for superconductivity above 260 K in lanthanum superhydride at megabar pressures
• Superconductivity to 262 kelvin via catalyzed hydrogenation of yttrium at high pressures
• Order parameter of MgB_2: a fully gapped superconductor
• Heat-capacity measurements under uniaxial pressure using a piezo-driven device
• AC-Calorimetry at High Pressure and Low Temperature
• Modulation calorimetry in diamond anvil cells I: heat flow models
• Modulation calorimetry in diamond anvil cells II: Joule-heating design and prototypes