Study on variation of second magnetization peak curve in a low temperature cubic superconductor, Ca₃Rh₄Sn₁₃

In the mixed phase of type-II superconductors, isothermal magnetization curves exhibit an anomalous feature, known as second magnetization peak (SMP). SMP is now widely accepted as an indication of order-disorder transition of vortex lattice. Most of the magnetic phase diagrams of type-II superconductors show SMP curve as temperature independent. In this paper, we have investigated the reason behind the non-monotonic variation of SMP in a low temperature type-II cubic superconductor, Ca₃Rh₄Sn₁₃ (T_c=8.37 K). The dc magnetization studies of Ca₃Rh₄Sn₁₃ single crystals were carried out using SQUID-Vibrating sample magnetometer. The non-monotonic variation of SMP anomaly with increase in temperature was observed in samples with high critical current densities. From X-ray diffraction studies and electron probe micro-analysis, it is concluded that the crystals which show non-monotonic variations of SMP in the phase diagrams have slightly higher concentration of point disorders and this causes the increase of critical current density.