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Hilscher, G.; Holland‐Moritz, E.; Holubar, T.; Jostarndt, H.-D.; Nekvasil, V.; Schaudy, G.; Walter, U.; Fillion, G.

doi:10.1103/physrevb.49.535

Cited by 117 publications

(79 citation statements)

References 70 publications

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“…Figure 5 plots the specific heat differences dC/T between the superconducting Pr247 and Y247 data, (C Pr247 /T and C Y247 /T , respectively) versus temperature. Comparing our results with the previous data obtained using Pr-based 123, 21 it is evident that the low-temperature specific heat data of PrBa 2 Cu 3 O 7 and PrBa 2 Cu 3 O 6 follow temperature trends, similar to those of as-sintered and vacuum-reduced Pr247, respectively. The common features include the λ-like enhancement in the former compounds and the broad C/T maximum in the latter.…”

Section: Resultssupporting

confidence: 76%

“…For example, as predicted from inelastic neutron scattering measurements of PrBa 2 Cu 3 O 6 , the crystal field splitting of this compound is E 1 = 19.7K and E 2 = 39.4K. 21 The low-temperature peak in the specific heat of the oxygen-removed superconducting sample is reasonably described by the Schottky anomaly (see Fig.5). The small discrepancy between the calculated curve and the experiment data is probably attributed to magnetic interactions among the Pr ions.…”

Section: Resultsmentioning

confidence: 84%

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Thermodynamic properties of superconducting and non-superconducting Pr2Ba4Cu7O15-δ compounds with metallic double chains

Konno¹,

Matsukawa²,

Sugawara³

et al. 2016

Physica C: Superconductivity and its Applications

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To examine the thermodynamic properties of Pr2Ba4Cu7O 15−δ compounds with metallic CuO double chains, we measured the specific heats of superconducting and non-superconducting polycrystalline samples at low temperatures (1.8-40 K) under various magnetic fields (up to 9 T). In the as-sintered non-superconducting sample, a λ−like enhancement in the specific heat measurement appeared near the antiferromagnetic transition temperature TN = 17 K. In contrast, the reduced superconducting sample with Tc,on = 26.5 K exhibited no obvious superconducting anomaly in its specific data, but a Schottky-like broad maximum appeared at low temperatures. The Schottky-like anomaly was attributed to low-lying quasi-triplet splitting of Pr 3+ ions under the crystal field effect.

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Section: Resultssupporting

confidence: 76%

Section: Resultsmentioning

confidence: 84%

Thermodynamic properties of superconducting and non-superconducting Pr2Ba4Cu7O15-δ compounds with metallic double chains

Konno¹,

Matsukawa²,

Sugawara³

et al. 2016

Physica C: Superconductivity and its Applications

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show abstract

“…The model is based on the single-ion states of Pr 3+ in the tetragonal crystalline electric field (CEF). We obtained these states by refining a model for the CEF using the observed energy spectra of polycrystalline PrBCO 6 [8]. The refinement gave a doublet ground state with a first excited state a few meV higher in energy, consistent with previous analyses [5,8].…”

supporting

confidence: 60%

“…We obtained these states by refining a model for the CEF using the observed energy spectra of polycrystalline PrBCO 6 [8]. The refinement gave a doublet ground state with a first excited state a few meV higher in energy, consistent with previous analyses [5,8]. To take into account the magnetic ordering at T < T Pr we included a molecular field.…”

mentioning

confidence: 72%

Coupled Magnetic Excitations in Single Crystal PrBa2Cu3O6.2

et al. 2001

Phys. Rev. Lett.

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The dispersion of the low-energy magnetic excitations of the Pr sublattice in PrBa2Cu3O6.2 is determined by inelastic neutron scattering measurements on a single crystal. The dispersion, which shows the effect of interactions with the Cu spin-waves, is well described by a model of the coupled Cu-Pr magnetic system. This enables values for the principal exchange constants to be determined, which suggest that both Pr-Pr and Cu-Pr interactions are important in producing the anomalously high ordering temperature of the Pr sublattice. Measurements of the Cu optic spin wave mode show that the inter-layer Cu-Cu exchange is significantly lower than in YBa2Cu3O6.2.PACS numbers: 71.28.+d, 74.72.Jt, 75.10.Dg, 78.70.Nx The anomalous properties of non-superconducting PrBa 2 Cu 3 O 6+x (PrBCO) [1] remain an outstanding problem in the field of cuprate superconductivity. Its magnetic properties are strikingly different from those of other members of the RBCO family (where R is a rare earth, Y or La). Long range antiferromagnetic order in both the Cu and Pr sublattices along with semiconducting resistivity persist over the entire range of oxygen doping 0 < x < 1, and the magnetic transition in the Pr sublattice occurs at a temperature T Pr an order of magnitude higher than for other rare earths in RBCO [2]. It is now generally believed that these anomalous properties are caused by a hybridisation of the Pr 4f and O 2p orbitals. In particular, an influential model of the electronic structure of PrBCO [3] explains the absence of superconductivity by a localisation of the holes in hybridised Pr-O bonds. Given the likelihood that the electronic and magnetic properties of PrBCO, including the occurrence of superconductivity [4], both depend on this hybridisation, detailed information on the strengths and symmetries of the magnetic interactions is desirable.In this Letter, we describe inelastic neutron scattering measurements of the magnetic excitations of PrBCO made for the first time on a single crystal. Using this data and a spin wave model of the coupled Cu-Pr system we have independently determined the magnitudes of the Pr-Pr, Cu-Pr and Cu-Cu interactions. We find that the Pr-Pr interaction is unexpectedly strong and would alone lead to T Pr being substantially higher than the rare-earth ordering temperature in other RBCO. We have also identified the effects of a pseudo-dipolar component to the Cu-Pr coupling on the magnetic excitations. Finally, we show that the inter-layer Cu-Cu exchange is reduced by a factor of two in PrBCO relative to YBCO.The experiments were performed on a crystal of PrBa 2 Cu 3 O 6.2 of mass 2 g prepared by top seeding a flux. The crystal mosaic was ∼ 1 • and T Pr = 13 K. Measurements on the triple-axis spectrometers TAS 6 at Risø and IN8 at the ILL were made at energy transfers up to 10 meV and 70 meV respectively. A horizontallyfocussing analyser was employed to increase the measured signal at the expense of some resolution in the scattering vector Q. The crystal was mounted in a 4 He cryostat and m...

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“…On closer inspection, however, it has been shown that these results can also be understood as an indication for Pr 3ϩ . For example, So "derholm et al 25 and Hilscher et al 26 were able to explain the reduced magnetic moment, taking a crystal field splitting of the 3 H 4 ground state of Pr 3ϩ into consideration. On the other hand, most band structure calculations 27 and highenergy spectroscopy experiments support a trivalent Pr atom.…”

Section: Introductionmentioning

confidence: 99%

X-ray absorption spectroscopy of detwinnedPrxY1−

et al. 1997

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UvA-DARE is a service provided by the library of the University of Amsterdam (http://dare.uva.nl) UvA-DARE (Digital Academic Repository)X-ray absorption spectroscopy of detwinned PrxY1-xBa2Cu3O7-y single crystals: electronic structure and hole distribution Merz, M.; Nücker, N.; Pellegrin, E.; Schweiss, P.; Schuppler, S.; Kielwein, M.; Knupfer, M.; Golden, M.S.; Fink, J. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Substituting Y in orthorhombic ͑Y,R)Ba 2 Cu 3 O 7 by any rare-earth element R has generally little effect on the superconducting properties. For RϭPr, however, superconductivity is completely suppressed. To understand this effect we have studied the unoccupied electronic structure of Pr x Y 1Ϫx Ba 2 Cu 3 O 7Ϫy (xϭ0.0, 0.4, 0.8) using polarization-dependent O 1s near-edge x-ray absorption spectroscopy of detwinned single crystals. We identify the hole states in the CuO 2 planes and the CuO 3 chains and give estimates of the relative contributions of the O 2p x , O 2p y , and O 2p z orbitals to these states. Along with the comparison of oxygen-rich (yϷ0.1) to the oxygen-depleted materials (yϷ0.9), this allows a test of the current theoretical explanations for the Pr-induced suppression of superconductivity. While we can rule out models involving hole filling or charge transfer between the planes and the chains, our data are consistent with approaches based on Pr 4f -O 2p hybridization. ͓S0163-1829͑97͒03313-4͔

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Valence of praseodymium inPrxY1−

Cited by 117 publications

References 70 publications

Thermodynamic properties of superconducting and non-superconducting Pr2Ba4Cu7O15-δ compounds with metallic double chains

Thermodynamic properties of superconducting and non-superconducting Pr2Ba4Cu7O15-δ compounds with metallic double chains

Coupled Magnetic Excitations in Single Crystal PrBa2Cu3O6.2

X-ray absorption spectroscopy of detwinnedPrxY1−

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