A spinel crystal structure exhibits unusual, pressure-induced superconductivity

Key Points:

• Researchers at the Chinese Academy of Sciences observed pressure-induced superconductivity in CuIr2S4, a spinel that is normally insulating below 230 K, by applying extremely high pressures up to 224 GPa.
• The study revealed two distinct superconducting phases, SC-I and SC-II, with a maximum transition temperature (Tc) of 18.2 K, the highest reported for bulk spinel superconductors.
• Superconductivity emerged only after multiple pressure-driven structural transitions, with evidence suggesting the SC-I phase may involve unconventional superconductivity linked to a broken-symmetry state.
• The research combined electrical transport measurements, synchrotron X-ray diffraction, Raman spectroscopy, and first-principles calculations to correlate superconductivity with crystal structure changes under pressure.
• This work opens new avenues for optimizing superconducting states in correlated materials through lattice tuning and high pressure, with future goals to understand the microscopic mechanisms and explore similar behaviors in related materials.