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Fisher, B.; Genossar, J.; Kuper, C.G.; Patlagan, L.; Reisner, G. M.; Knizhnik, A.

doi:10.1103/physrevb.47.6054

Cited by 128 publications

(75 citation statements)

References 22 publications

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“…As mentioned in the introduction Ca doping reduces the CuO chain order [88,91]. Therefore, the decrease of the peak in Fig.…”

Section: Pressure Induced Hole Doping Of the Cuo 2 Planesmentioning

confidence: 99%

“…For instance it is now known that doping with Ca does reduce the T c,max value [8,11,49] which implies that with increasing Ca-content the T c value is not only determined by the increasing hole doping, but is influenced by the T c suppression from Ca, too. In addition with fixed annealing conditions the resulting oxygen content x of a Y 1-y Ca y Ba 2 Cu 3 O x is reduced [86] by ≈y/2, and for larger Ca contents Ca does no longer tend to dope the Y-site only [87][88][89][90]. The orthorhombicity of Y 1-y Ca y Ba 2 Cu 3 O x is influenced by Ca, too, because with increasing Ca content oxygen atoms in the vicinity of a Ca atom tend to occupy not only O(1) sites (in chain) but also O(5) sites (out of chain) [88,91].…”

Section: Introductionmentioning

confidence: 99%

“…In addition with fixed annealing conditions the resulting oxygen content x of a Y 1-y Ca y Ba 2 Cu 3 O x is reduced [86] by ≈y/2, and for larger Ca contents Ca does no longer tend to dope the Y-site only [87][88][89][90]. The orthorhombicity of Y 1-y Ca y Ba 2 Cu 3 O x is influenced by Ca, too, because with increasing Ca content oxygen atoms in the vicinity of a Ca atom tend to occupy not only O(1) sites (in chain) but also O(5) sites (out of chain) [88,91]. As a consequence the disorder in the CuO chain sublattice is increased with increasing Ca content, making it more difficult to achieve a well ordered CuO chain system in the ortho I or the ortho II phase.…”

Section: Introductionmentioning

confidence: 99%

“…Because of the small size of the single crystals we could not determine the oxygen content x by weighing or by chemical methods. Therefore, x was estimated from the annealing conditions, using Ca content dependent isotherm curves 2 O log P vs. oxygen content [87,88]. The absolute oxygen contents obtained from these isotherms have been checked for selected samples via neutron scattering and are reliable enough to show trends in T c (x) and dT c /dp(x).…”

Section: Introductionmentioning

confidence: 99%

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The effect of chemical doping and hydrostatic pressure on Tc of Y1−yCayBa2Cu3Ox single crystals

Schlachter

Fietz²,

Grube³

et al. 1999

Physica C: Superconductivity

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We performed susceptibility measurements on Y 1-y Ca y Ba 2 Cu 3 O x single crystals under high He pressure. For each Ca content various samples with different oxygen contents have been prepared to probe the influence of Ca on T c (x), dT c /dp(x) and T c,max . Starting from the parabolic T c (n h ) behavior we calculated n h values from T c and T c,max for each sample. It is shown that in the overdoped region dT c /dp can be described by a pressure induced charge transfer with dn h /dp ≈ 3.7⋅10 -3 GPa -1 and a dT c,max /dp value of 0.8 K/GPa, irrespective of the Ca content. In the underdoped region additional pressure effects lead to a peak in dT c /dp at ≈0.11 holes/CuO 2 plane. However, with increasing Ca content this peak is strongly depressed. This is explained in terms of an increasing disorder in the CuO chain system due to doping. Deviations in dT c /dp at very low n h values can be assigned to the ortho II ordering in the CuO chain system.

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“…As mentioned in the introduction Ca doping reduces the CuO chain order [88,91]. Therefore, the decrease of the peak in Fig.…”

Section: Pressure Induced Hole Doping Of the Cuo 2 Planesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The effect of chemical doping and hydrostatic pressure on Tc of Y1−yCayBa2Cu3Ox single crystals

Schlachter

Fietz²,

Grube³

et al. 1999

Physica C: Superconductivity

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show abstract

“…Details of the experimental setup, surface preparations and methodology of data analysis for the STS studies have been described elsewhere [5][6][7]14,15] were 68 K, 64 K, 59 K, 42 K and 74 K, respectively. We note that the p value for a given Ca-doping level x depends on the oxygen annealing process [19], and that there is a maximum T c value for a given x, T c,max (x), which were empirically determined to be 93.5 K, 89.0 K, 82.9 K and 82.9 K for x = 0, 0.10, 0.20 and 0.30, respectively [19]. Hence, the p values of Ca-doped Y-123 samples are estimated from T c,max (x) and the empirical formula [20] [7,15].…”

Section: Methodsmentioning

confidence: 99%

Scanning Tunneling Spectroscopic Studies of the Low-Energy Quasiparticle Excitations in Cuprate Superconductors

Yeh

Teague

et al. 2012

J Supercond Nov Magn

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We report scanning tunneling spectroscopic (STS) studies of the low-energy quasiparticle excitations of cuprate superconductors as a function of magnetic field and doping level. Our studies suggest that the origin of the pseudogap (PG) is associated with competing orders (COs), and that the occurrence (absence) of PG above the superconducting (SC) transition T c is associated with a CO energy  CO larger (smaller) than the SC gap  SC . Moreover, the spatial homogeneity of  SC and  CO depends on the type of disorder in different cuprates: For optimally and under-doped YBa 2 Cu 3 O 7 (Y-123), we find that  SC <  CO and that both  SC and  CO exhibit long-range spatial homogeneity, in contrast to the highly inhomogeneous STS in Bi 2 Sr 2 CaCu 2 O 8+x (Bi-2212). We attribute this contrast to the stoichiometric cations and ordered apical oxygen in Y-123, which differs from the non-stoichiometric Bi-to-Sr ratio in Bi-2212 with disordered Sr and apical oxygen in the SrO planes. For Ca-doped Y-123, the substitution of Y by Ca contributes to excess holes and disorder in the CuO 2 planes, giving rise to increasing inhomogeneity, decreasing  SC and  CO , and a suppressed vortex-solid phase. For electron-type cuprate Sr 0.9 La 0.1 CuO 2 (La-112), the homogeneous  SC and  CO distributions may be attributed to stoichiometric cations and the absence of apical oxygen, with  CO <  SC revealed only inside the vortex cores. Finally, the vortex core radius ( halo ) in electron-type cuprates is comparable to the SC coherence length  SC , whereas  halo ~ 10 SC in hole-type cuprates, suggesting that  halo may be correlated with the CO strength.The vortex-state irreversibility line in the magnetic field versus temperature phase diagram also reveals doping dependence, indicating the relevance of competing orders to vortex pinning.

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Growth and Electric Transport of Ca-doped PrBa2Cu3O7-δSingle Crystals

Łuszczek

Sadowski

2001

Cryst. Res. Technol.

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Crystal growth of Ca‐doped PrBa2Cu3O 7‐ δ (Pr‐123) single crystals by slow cooling of Pr3O11‐CaCO3‐BaCO3‐CuO melts (self‐flux technique) in ambient air atmosphere was studied. As the first approach the growth of Ca‐free crystals in Al2O3 and ZrO2 crucibles was investigated. The best quality crystals with the average size of 5 x 5 x 0.2mm3 were obtained from Al2O3 crucibles for Ba/Cu = 0.41 and 15 wt.% (2.41 mol.%) of stoichiometric Pr‐123 solute in the melt. Next, using CaCO3 as calcium source (0.09 ‐12.68 wt.%), the good quality Pr1‐x CaxBa2Cu3O 7‐ δ crystals with 0 ≤ x ≤ 0.26 were grown in the Al2O3 crucibles from the solution with fixed value of Ba/Cu = 0.41. The oxygenated single crystals with size up to 5 x 8 x 0.2 mm3 were used for electric transport investigations from four‐probe resistivity measurements. The temperature dependence of resistivity of Ca‐doped Pr‐123 crystals is typical for systems with locallized states and, in principle, follows the Mott law for variable‐range hopping (VRH).

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Effects of substituting calcium for yttrium on the properties ofYBa2Cu3

Cited by 128 publications

References 22 publications

The effect of chemical doping and hydrostatic pressure on Tc of Y1−yCayBa2Cu3Ox single crystals

The effect of chemical doping and hydrostatic pressure on Tc of Y1−yCayBa2Cu3Ox single crystals

Scanning Tunneling Spectroscopic Studies of the Low-Energy Quasiparticle Excitations in Cuprate Superconductors

Growth and Electric Transport of Ca-doped PrBa2Cu3O7-δSingle Crystals

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