Distinction between the normal-state gap and superconducting gap of electron-doped cuprates

Abstract

We report the study of temperature- and magnetic-field dependent in-plane tunneling conductance on the electron-doped Nd(1.85)Ce(0.15)CuO(4-y) and Pr(1-x)LaCe(x)CuO(4-y) single crystals. The previously reported normal state gap (NSG) Delta(ps) and superconducting gap Delta(sc) were observed simultaneously in superconducting state. Combined with an investigation on the evolution of low-energy spectral weight with temperature, our data present evidence for electron-doped cuprates that Delta(ps) and Delta(sc) are most possibly two different energy scales with very different field dependencies, and that superconductivity is condensed from the residual quasiparticle density of states (DOS) of the NSG state.