We investigate the thermal-driven charge density wave (CDW) transition of two cubic superconducting intermetallic systems Lu(Pt1-xPdx)2In and (Sr1-xCax)3Ir4Sn13 by means of x-ray diffraction technique. A detailed analysis of the CDW modulation superlattice peaks as function of temperature is performed for both systems as the CDW transition temperature T_CDW is suppressed to zero by an non-thermal control parameter. Our results indicate an interesting crossover of the classical thermal-driven CDW order parameter critical exponent from a three-dimensional universality class to a mean-field tendency, as T_CDW vanishes. Such behavior might be associated with presence of quantum fluctuations which influences the classical second-order phase transition, strongly suggesting the presence of a quantum critical point (QCP) at T_CDW = 0. This also provides experimental evidence that the effective dimensionality exceeds its upper critical dimension due to a quantum phase transition.
@article{arxiv.1912.05669,
title = {Unveiling charge density wave quantum phase transitions by x-ray diffraction},
author = {F. B. Carneiro and L. S. I. Veiga and J. R. L. Mardegan and R. Khan and C. Macchiutti and A. Lopez and E. M. Bittar},
journal= {arXiv preprint arXiv:1912.05669},
year = {2020}
}