Heat Capacity of Single Crystal CuxTiSe2 Superconductors

We present heat capacity measurements on a series of superconducting Cu\(_x\)TiSe\(_2\) single crystals with different Cu content down to 600 mK and up to 1 T performed by ac microcalorimetry. The samples cover a large portion of the phase diagram from an underdoped to a slightly overdoped region with an increasing superconducting critical temperature and the charge density wave (CDW) order gradually suppressed. The electronic heat capacity as a function of normalized temperature \(T/T_c\) shows no difference regardless of the concentration of copper, i.e., regardless of how much the CDW order is developed in the samples. The data analysis reveals consistently a single s-wave gap with an intermediate coupling strength \(2\Delta/k_BT_c\) = 3.7 for all samples.