Superconducting Gap Anisotropy in Nd$_{1.85}$Ce$_{0.15}$CuO$_4$: Results   from Photoemission
  We have performed angle resolved photoelectron spectroscopy on the electron doped cuprate superconductor Nd$_{1.85}$Ce$_{0.15}$CuO$_4$. A comparison of the leading edge midpoints between the superconducting and normal states reveals a small, but finite shift of 1.5-2 meV near the ($\pi$,0) position, but no observable shift along the zone diagonal near ($\pi$/2,$\pi$/2). This is interpreted as evidence for an anisotropic superconducting gap in the electron doped materials, which is consistent with the presence of d-wave superconducting order in this cuprate superconductor. 
N.P. Armitage, D.H. Lu, D.L. Feng, C.Kim, A.Damascelli, K.M. Shen, F.   Ronning, Y. Onose, Y. Taguchi, Y. Tokura, and Z.-X. Shen