Destruction of superconductivity inNd2−xCexCuO

Abstract

We have measured the resistivity and Hall coefficient of Nd 2Ϫx Ce x CuO 4Ϫ␦ ͑NCCO͒ thin films sequentially damaged by ion irradiation. The T c of the NCCO decreases linearly with residual resistivity and extrapolates to zero at R ᮀ /(unit cell)Ϸ5Ϫ10 k⍀, results similar to Y-Ba-Cu-O. We suggest that the physical basis for this behavior in NCCO may be disorder effects in a homogeneous two-dimensional superconductor. Unusual behavior of the Hall coefficient gives further evidence that NCCO may be a two-carrier conductor.

Anomalous impurity effects in nonadiabatic superconductors

“…Our results can be of particular interest in light of the disorder dependence of T c recently observed in the fullerene compound K 3 C 60 and in the electron doped cuprate Nd 2−x Ce x CuO 4−δ [11,12]. Both compounds have a well-established s-wave symmetry of the gap, hence the disorder induced suppression of T c cannot be explained in terms of d-wave pairing [13].…”

“…Given the above situation it could be therefore difficult to decide whether the T c suppression observed in K 3 C 60 [11] and in Nd 2−x Ce x CuO 4−δ [12] should be ascribed to anisotropies of the order parameter or instead to the nonadiabatic el-ph interaction. Here, we propose that a more suitable quantity to look at could be the ion-mass dependence of the critical temperature.…”

“…It would be therefore important to measure the isotope coefficient and its evolution with the amount of disorder in the two s-wave superconductors K 3 C 60 and Nd 2−x Ce x CuO 4−δ . Such a measurement could in fact decide whether the observed T c suppression in these materials [11,12] is given by anisotropy or by the nonadiabatic regime of the el-ph interaction. We note moreover that a measurement of α Tc vs T c /T c0 could provide an experimental tool for an estimation of the typical momentum scattering Q c in addition to the one obtained by tunneling measurements [22].…”

Hidden Fermi-liquid Charge Transport in the Antiferromagnetic Phase of the Electron-Doped Cuprate Superconductors

“…In contrast, at the same nominal doping level, A log and A 0 are nearly an order of magnitude larger for the electron-doped compounds; similar to A 2 , these coefficients exhibit power-law doping dependences [25]: NCCO [34] NCCO (film) [33] PCCO (film) [36] PCCO (film) [37] PCCO (film) [38] PCCO (film) [39] PLCCO [28] LCCO (film) [40] LSCO [24] YBCO [7] YBCO [24] YBCO [41] La-Bi2201 [29] La-Bi2201 [27] Hg1201 [15] LYCO [35] NCCO this work NCCO [26] NCCO [31] NCCO [32] FIG. 2.…”

“…Starting with new data for a sample of the archetypal electron-doped cuprate Nd 2−x Ce x CuO 4+δ (NCCO) that exhibits robust AF order (x = 0.10; superconductivity in NCCO appears for x ≈ 0.13 [4]), we follow the evolution of these three contributions as a function of temperature and doping for a large number of compounds: electron-doped NCCO [26,[31][32][33][34], La 2−x Y x CuO 4+δ (LYCO) [35], Pr 2−x Ce x CuO 4+δ (PCCO) [36][37][38][39], Pr 1.3−x La 0.7 Ce x CuO 4+δ (PLCCO) [28], and La 2−x Ce x CuO 4+δ (LCCO) [40], and hole-doped La 2−x Sr x CuO 4 (LSCO) [6,24], YBCO [7,24,41] and Bi 2 Sr 2−x La x Cu 2 O 8+δ (La-Bi2201) [27,29]. Representative resistivity data are shown in Fig.…”