Vortex phase diagram study in the superconductor Ca₃Ir₄Sn₁₃

We present the vortex phase diagram for a single crystal of a low T c superconductor, Ca 3 Ir 4 Sn 13 explored via detailed ac magnetic susceptibility ( χ ′ ( H , T ) ) and ac electrical resistivity ( ρ ( H , T )) measurements. We observe a sharp peak effect (PE) phenomenon close to the superconducting-normal phase transition. This is in contrast to the findings for a second crystal of Ca 3 Ir 4 Sn 13 in which a second magnetization peak was observed. Across the PE region, both the magnetization as well as the resistivity response depend on the thermomagnetic history of the sample. Further, the two measurement techniques (ac susceptibility and resistivity) reveal the occurrence of PE in different regions of the H − T phase space. In the high-field low-temperature region ( H > 42 kOe and T < 3 K), the χ ′ ( H , T ) scans reveal a PE feature which is not observed in the ρ ( H , T ) data. On the other hand, the ρ ( H , T ) data display a sharp PE in the low-field high-temperature region ( H < 23 kOe and T > 5 K) wherein the χ ′ ( H , T ) measurements do not show any signature of the PE. Two characteristic H – T regions have been identified in which only one of the two measurement techniques ( χ ′ ( H , T ) and ρ ( H , T )) assists to identify the PE boundary.