Possible quantum fluctuations in the vicinity of the quantum critical point of (Sr, Ca)3Ir4Sn13 revealed by high-energy x-ray diffraction

We explore the evolution of the structural phase transition of (Sr, Ca)(3)Ir4Sn13, a model system to study the interplay between structural quantum criticality and superconductivity, by means of high-energy x-ray diffraction measurements at high pressures and low temperatures. Our results confirm a rapid suppression of the superlattice transition temperature T* against pressure, which extrapolates to zero at a critical pressure of approximate to 1.79(4) GPa. The temperature evolution of the superlattice Bragg peak in Ca3Ir4Sn13 reveals a drastic decrease of the intensity and an increase of the linewidth when T -> 0 K and p -> p(c). Such anomaly is likely associated with the emergence of quantum fluctuations that disrupt the formation of long-range superlattice modulation. The revisited temperature-pressure phase diagram of (Sr, Ca)(3)Ir4Sn13 thus highlights the intertwined nature of the distinct order parameters present in this system and demonstrates some similarities between this family and the unconventional superconductors.