BCS d-wave behavior in the terahertz electrodynamic response of electron-doped cuprate superconductors

Although cuprate superconductors have been intensively studied for the past decades, there is no consensus regarding the microscopic origin of their superconductivity. In this paper, we measure the low-energy electro-dynamic response of slightly underdoped and overdoped La2-xCexCuO4 thin films using time-domain terahertz (THz) spectroscopy to determine the temperature and field dependence of the superfluid spectral weight. We show that the temperature dependence obeys the relation n(s) proportional to 1 - (T/T-c)(2), typical for dirty limit BCS-like d-wave superconductors. Furthermore, the magnetic field dependence was found to follow a sublinear root B form, which supports predictions based on a d-wave symmetry for the superconducting gap. These observations imply that the superconducting order in these electron-doped cuprates can be well described in terms of a disordered BCS d-wave formalism.