Phase diagram for the electron-doped Nd2−xCexCuOy superconducting system

Singh, Okram G.; Padalia, B. D.; Prakash, Om; Suba, K.; Narlikar, A. V.; Gupta, LC

doi:10.1016/0921-4534(94)90028-0

Cited by 32 publications

(17 citation statements)

References 21 publications

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“…In other words, the oxygen reduction changed the local bonding, coordination or occupancy of oxygen leading to a strong distortion of the Nd͑Ce͒ sublattice. [3][4][5][6][7][8] Furthermore, our experiment showed that, from a different point of view, oxygen over-reduction is not directly correlated to phase decomposition. 9,15,16 It should be mentioned that there is a threshold annealing temperature, ranging from 350 to 600°C depending upon the microstructure of the films, for oxygen diffusion to take place.…”

Section: Stc Los Alamos National Laboratory Los Alamos New Mexico mentioning

confidence: 67%

“…This has been well demonstrated in the p-type ͑hole-doped͒ cuprates, such as YBa 2 Cu 3 O 7Ϫ␦ , La 2Ϫx Sr x CuO 4 , and BiSrCaCuO. [3][4][5][6][7][8] Recently, using NCCO films with different oxygen concentrations, we conducted a systematic study on the oxygen doping effect finding unusual properties indicative of the existence of both electron and hole carriers in NCCO. 2 One of the reasons for this lack of understanding is the delicate oxygen reduction process.…”

Section: Stc Los Alamos National Laboratory Los Alamos New Mexico mentioning

confidence: 76%

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Characteristics of oxygen over-reduced Nd1.85Ce0.15CuO4−y films

Mao

Jiang

et al. 1995

Applied Physics Letters

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Section: Stc Los Alamos National Laboratory Los Alamos New Mexico mentioning

confidence: 67%

Section: Stc Los Alamos National Laboratory Los Alamos New Mexico mentioning

confidence: 76%

Characteristics of oxygen over-reduced Nd1.85Ce0.15CuO4−y films

Mao

Jiang

et al. 1995

Applied Physics Letters

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“…The vacuum for the Hamiltonian ͑1͒ is the electron configuration Cu 3d 10 It is known that the relative ͑per one elementary CuO 2 cell͒ carrier concentration x, which corresponds to the maximum T c , is xϭ1.1-1.25 for hole HTSC, 1,46 and xϭ0.83-0.88 for electron HTSC. 1,47 Below, we deal with this range of concentrations.…”

Section: Pairing-correlation Functions In the Emery Modelmentioning

confidence: 99%

Pairing correlations in two-dimensional large-size Cu-O clusters: Nonlocal world-line Monte Carlo algorithm

Kashurnikov¹

1996

Phys. Rev. B

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A Monte Carlo world-line algorithm for a CuO 2 plane based on a breakup of the plane into five-site cells, CuO 4 has been suggested. The algorithm has fast convergency and gives the possibility of investigating the superconducting state symmetry. The calculation of pairing correlation functions was made with an advent of additional imaginary-time slices to the Monte Carlo scheme. The characteristics of a two-dimensional Cu-O cluster with number of sites N a ϭ768 (16ϫ16 CuO 2 cells͒ were calculated. It has been shown within the chosen interval of parameters of the Emery Hamiltonian (U d ϭ6t, ϭ1Ϫ3t, U p ϭVϭ0), temperatures (Tу0.125t), and carrier concentrations (0.7рxр1.5) that ͑i͒ the long-range off-diagonal order associated with the superconducting state was not observed in the thermodynamic limit in any pairing channels and ͑ii͒ a tendency to divergence in s* channels and d x 2 Ϫy 2 channels, which is noted as the temperature decreases, is due to the antiferromagnetic ordering rather than the superconducting pairing. If the carrier concentration x is equal to 1.0 ͑undoped dielectric state͒ the pairing correlations have maximum amplitude and demonstrate clear antiferromagnetic ordering in the copper sublattice, and the characteristic correlation length is close to the earlier-reported antiferromagnetic length.

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“…[1][2][3][4][5][6][7][8][9] The replacement of Ce by Th also produces a similar result, albeit with a lower critical temperature, T c . 1,10-12 A partial replacement of O 2− by monovalent F − , causing the CuO 2 plane to be doped with an additional electron, also makes the Ln 2 Cu(O 4−y F y ) system superconducting (SC) [13][14][15][16][17][18] It was reported by Ayoub et al 19 and Felner et al 20 that a partial (3 at%) substitution of nonmagnetic higher valent M 3+ (In 3+ or Ga 3+ ) for Cu, leading to the optimum 0.03 carrier addition per formula unit, induced superconductivity with T c onset of 23 K for In and 20 K for Ga in the pristine non-SC Nd 1.88 Ce 0.12 CuO 4−δ .…”

Section: Introductionmentioning

confidence: 98%

ON Zr SUBSTITUTION IN T′-TYPE Nd–Ce–Cu–O SYSTEM

et al. 2000

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The effect of tetravalent Zr substitution (≤ 2 at%) at the Cu site in T -type Nd 2−x CexCuO 4−δ (NCCO), x = 0.12, 0.14, 0.15, on the superconducting (SC) behavior is investigated. EDX analyses of the samples clearly reveal the presence of only ∼ 0.5 at% Zr in the T -phase. Irrespective of the Ce content (0.12 ≤ x ≤ 0.15), Tc is found to depress with Zr. A fall in Tc of ∼ 2 K is observed due to 0.5 at% Zr 4+ in x = 0.14 samples, while the NCCO (x = 0.12) on substitution of Zr (expected to dope 2 electrons per Zr 4+ and induce superconductivity) remains non-SC. The reported conjecture regarding Tc inducement due to the carrier addition of 0.03 (per formula unit) arising from 3 at% In 3+ (or Ga 3+ ) substitution for Cu in Nd 1.88 Ce 0.12 CuO 4−δ [Ayoub et al., Physica C170, 211 (1990); Felner et al., Phys. Rev. B40, 11366 (1989)] is not applicable for the Zr-substituted NCCO.

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Phase diagram for the electron-doped Nd2−xCexCuOy superconducting system

Cited by 32 publications

References 21 publications

Characteristics of oxygen over-reduced Nd1.85Ce0.15CuO4−y films

Characteristics of oxygen over-reduced Nd1.85Ce0.15CuO4−y films

Pairing correlations in two-dimensional large-size Cu-O clusters: Nonlocal world-line Monte Carlo algorithm

ON Zr SUBSTITUTION IN T′-TYPE Nd–Ce–Cu–O SYSTEM

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