Effects of 2.6-GeV U ion irradiation on the superconductivity of the kagome superconductors Cs V3 S b5 and Cs(V0.93 N b0.07)3 S b5

We have investigated the effect of 2.6-GeV U irradiation on the superconductivity of CsV3Sb5 and Cs(V0.93Nb0.07)3Sb5 single crystals by using resistivity and magnetization measurements. The critical transition temperature for CsV3Sb5 crystal is enhanced up to 4.3 K after irradiation with a dose of Bφ=2.0T, while the critical current density is increased up to ∼0.8×104A/cm2 after irradiation with a dose of Bφ=0.5T under self-field at 2.0 K, which is about four times larger than that for the pristine crystal under the same condition. For Cs(V0.93Nb0.07)3Sb5 crystal, the critical transition temperature remains almost constant up to Bφ=2.0T, followed by monotonic suppression with further increase of dose. Besides the enhanced critical current density, we observe an anomalous peak effect in the magnetic hysteresis loop close to zero field at low irradiation doses, which can be interpreted by the matching effect in irradiated Cs(V0.93Nb0.07)3Sb5 crystals.