Pressure-induced superconductivity in itinerant antiferromagnet CrB2

The recent discovery of superconductivity up to 32 K in the pressurized MoB2 revives the interests in exploring novel superconductors in transition-metal diborides isostructural to MgB2. Although the Mo 4d-electrons participate in Cooper pairing, the electron-phonon coupling remains the dominant mechanism for the emergence of superconductivity in MoB2. To explore possible superconductivity driven by unconventional pairing mechanism, we turn our attention to an itinerant antiferromagnet CrB2. Here we report on the discovery of superconductivity up to 7 K in CrB2 via the application of external pressure. Superconductivity is observed after the antiferromagnetic transition at TN ~ 88 K under ambient pressure is completely suppressed. Then, the superconducting Tc increases monotonically with pressure and this evolution takes place without a structural transition in the sample. Since the proximity of superconductivity to an antiferromagnetic order, the quantum criticality and unconventional superconductivity may exist in CrB2. Current study would promote further studies and explorations of novel superconductors in other transition-metal diborides.