  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.
