COEXISTENCE OF ANTIFERROMAGNETIC ORDERING AND HIGH-Tc SUPERCONDUCTIVITY IN ELECTRON-DOPED SUPERCONDUCTOR Nd2-xCexCuO4

Muon spin relaxation and magnetic susceptibility measurements were performed for the electron-doped superconductor Nd2-xCexCuO4 (NCCO) with a particular attention to the vicinity of the boundary in phase diagram between the antiferromagnetic (AF) and the superconducting phases. The phase diagram exhibits a competitive change in the volume fraction between the two phases around the phase boundary; a dramatic decrease of the AF phase and a sudden appearance of bulk superconductivity upon doping beyond x=0.13. However, the spatial coexistence of both phases is also suggested around the boundary. In contrast to the hole-doped system, the onset of Tc is approximately independent of doping in the underdoped region of NCCO. 8 refs.