Evidence from the Low-Temperature Specific Heat for d-Ware Pairing Symmetry in Pr_1.85Ce_0.15CuO₄

Abstract

Recently, possible evidence from the low-temperature specific heat (LTSH) for the lines of nodes in the superconducting order parameter of cuprate superconductors has attracted much attention and is still a controversial issue. To clarify this issue, N-type Pr1.85Ce0.15CuO4 has been investigated by means of X-ray diffraction, electrical resistivity, magnetic-susceptibility and LTSH measurements. X-ray diffraction pattern shows that the sample contains a single T' phase, and the superconducting transition temperature Tcm taken with the onset of diamagnetism in magnetic-susceptibility measurement is nearly 20 K. The data shows clear evidence for an αT2 term at zero magnetic field in LTSH of Pr1.85Ce0.15CuO4, and is consistent with d-wave superconductivity. Furthermore, this result is discussed and compared with those results observed in LTSH of La1.78Sr0.22CuO4.