Second harmonic AC calorimetry technique within a diamond anvil cell

Area of Science:

• Condensed matter physics
• Materials science
• High-pressure physics

Background:

• High pressure tuning of matter's energy density induces exotic properties like superconductivity.
• Specific heat measurements are crucial for characterizing phase transitions but challenging within diamond anvil cells (DACs).
• Existing methods for specific heat measurement in DACs are limited and experimentally demanding.

Purpose of the Study:

• To develop a novel, versatile method for measuring specific heat within a DAC.
• To overcome the experimental challenges associated with high-pressure specific heat studies.
• To demonstrate the applicability of the new method for probing superconductivity.

Main Methods:

• Developed a DAC-independent specific heat measurement technique.
• Ensured compatibility with existing high-pressure resistance measurement setups.
• Performed proof-of-concept measurements on the MgB2 superconductor.

Main Results:

• Successfully measured specific heat anomalies in MgB2 at its superconducting transition temperature (Tc).
• Demonstrated bulk superconductivity in MgB2 under high pressure.
• Established a new capability for specific heat measurements at higher pressures than previously achievable.

Conclusions:

• The novel method provides a robust approach for high-pressure specific heat studies.
• This technique facilitates the exploration of exotic states of matter under extreme conditions.
• The MgB2 results validate the method's potential for discovering new high-pressure phenomena.