Current Research Issues for the Electron-Doped Cuprates

This work attempted to summarize very briefly the current status of some of the research on the electron-doped cuprates, in particular and Nd 2-x Ce x CuO 4 and Pr 2-x Ce x CuO 4 . Normal-state and superconducting properties were explored in parallel with the hole-doped single-layer cuprate La 2-x Sr x CuO 4 . The differences between the two systems were emphasized. One of the main conclusions related to the symmetry of the gap was the fact that there is no clear evidence of a d-wave component (even an anisotropic gap) in the electron-doped cuprates, most of the measurements being consistent with an s-wave BCS gap. However, it is important to mention that many of the experiments used to check the symmetry of the gap in the hole-doped systems have never been attempted successfully in the electron-doped materials. Most of them probably failed because of detrimental material issues. Phase-sensitive experiments should be attempted more seriously in the future to clarify the nature of the superconducting state in the electron-doped cuprates.