CuIr2S4 spinel achieves record 18.2 K superconductivity
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- Bijuan Chen and colleagues at the Center for High Pressure Science & Technology Advanced Research, Chinese Academy of Sciences observed pressure-induced superconductivity in CuIr2S4, a spinel that becomes an insulator below ~230 K due to charge ordering.
- CuIr2S4 developed two distinct superconducting phases (SC-I and SC-II) under pressures up to 224 GPa—more than 2 million times atmospheric pressure—reached via diamond anvil cells.
- The maximum transition temperature reached 18.2 K, surpassing the previous bulk spinel benchmark of 13.7 K and setting a new record for bulk spinel superconductors.
- SC-I showed evidence of a broken-symmetry state, pointing to potentially unconventional superconductivity, while SC-II emerged as a new ultrahigh-pressure phase distinct from SC-I.
- Combining electrical transport measurements, synchrotron X-ray diffraction, and Raman spectroscopy with first-principles calculations linked superconductivity to a sequence of pressure-driven structural transitions.
- Published in Physical Review Letters, the work introduces a new approach to optimizing superconductivity in frustrated correlated materials, with the team next aiming to understand the microscopic pairing mechanisms in each phase and to find similar behavior in other frustrated spinels.
Why it matters: The 18.2 K record in CuIr2S4 tops the bulk spinel benchmark and comes from a charge-ordered insulator turned superconductor—reversing the expectation that pressure initially strengthens the insulating state. The two-phase behavior with hints of unconventional pairing gives materials physicists a new system for studying how lattice tuning drives superconductivity in correlated materials.
