Can we probe the pure charge-density-wave signal in superconducting cuprates: Developing the transition-edge sensor for resonant soft X-ray scattering

Cuprates have been extensively studied since the first discovery of their high-Tc superconductivity in 1986. Nevertheless, its mechanism still remains a profound mystery. Meanwhile, in 2-dimensional hole-doped cuprates such as YBCO, charge density wave (CDW) correlation has been found to compete with superconductivity below Tc, which suggests that the CDW plays a crucial role to understand such mechanism of the superconductivity. Cu L-edge resonant soft X-ray scattering (RSXS) has been appreciated as a very efficient technique that can directly probe the CDW. However, due to CDW’s intrinsically weak correlation and correspondingly weak signal, this experimental technique has been experiencing difficulties associated with huge Cu fluorescence background. Thus, one of the biggest challenges in RSXS measurements is how to eliminate such fluorescence background. For this purpose, we have been developing a RSXS setup with a state-of-the-art energy-resolving detector, so called transition-edge sensor (TES), at beamline 13-3 of the Stanford Synchrotron Radiation Lightsource (SSRL). In this talk, we will show the efficiency of the new setup as well as how it can contribute to solving profound scientific questions in high-Tc superconductivity.