| 1. |
- Bäckström, Joakim, et al.
(författare)
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Raman scattering in \RmYBa$_2$Cu$_4$O$_8$ and PrBa$_2$Cu$_4$O$_8$ : Indications of pseudogap effects in non-superconducting \RmPrBa$_2$Cu$_4$O$_8$
- 2000
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 61, s. 7049-7054
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Tidskriftsartikel (refereegranskat)abstract
- By analysis of the Raman spectra of superconducting YBa2Cu4O8 (Y-124), we observe a suppression of low-energy electronic density of states that we link to changes in the linewidth of the Ba-phonon mode. These effects occur at a temperature below 150 K, where also anomalies in resistivity and other physical properties take place. We argue that these changes in the Raman spectra of Y-124 are connected to the opening of a pseudogap. Analogous anomalies in resistivity and the Ba-phonon width in the nonsuperconducting homologue PrBa2Cu4O8 (Pr-124) below 150 K suggest that similar pseudogap effects can occur without a following transition to a superconducting state at a lower temperature.
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| 2. |
- Bäckström, Joakim, et al.
(författare)
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Raman scattering in YBa2Cu4O8 and PrBa2Cu4O8 - indications of pseudogap effects in non-superconducting PrBa2Cu4O8
- 2000
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Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 341, s. 2251-2252
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Tidskriftsartikel (refereegranskat)abstract
- By analysis of the temperature evolution of Raman spectra, we connect an observed supression in low-energy electronic density of states to an anomalous sharpening of the Ba-phonon mode in superconducting YBa2Cu4O8 (Y-124) at around T=150 K. We link the supression of electronic excitations to an opening of a pseudogap. Similar effects observed for the Ba-phonon mode at roughly the same temperature in non-superconducting PrBa2Cu4O8 (Pr-124) suggests that a pseduogap opens up around 150 K also in this material.
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| 3. |
- Osada, M., et al.
(författare)
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Photoinduced effects and oxygen dynamics in YBa2Cu3Ox
- 2001
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Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 364, s. 545-548
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Tidskriftsartikel (refereegranskat)abstract
- Oxygen-deficient YBa2Cu3Ox (Y123) exhibits persistent photoconductivity when illuminated by visible light. We have investigated resonant Raman spectra as a function of excitation wavelength and temperature, which shed new light on photoinduced effects and chain oxygen dynamics in Y123. Experimental evidence suggests that the mechanism behind the unusual photoinduced effects primary involves photoinduced oxygen ordering. Our Raman data also constitute the non-diffraction observations of the superstructure phase transition in Y123. (C) 2001 Elsevier Science B.V. All rights reserved.
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| 4. |
- Osada, M., et al.
(författare)
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Resonant Raman scattering and photoinduced metastability in oxygen-deficient YBa2Cu3Ox
- 2000
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Ingår i: Physica C. ; 338, s. 157-160
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Tidskriftsartikel (refereegranskat)abstract
- We studied the photoinduced metastable states in oxygen-deficient YBa2Cu3Ox (Y123) (x = 6.35-6.87). The states are identified by the intensity dependences of CuO-chain resonance on photo irradiation and temperature. Below room temperature (RT) the CuO-chain resonance can be completely suppressed by irradiation with visible light polarized along the CuO chains, indicating photo-assisted oxygen ordering. Above RT, the resonance intensity returns and saturates at T > 100 degrees C. This behavior exactly reflects the temperature dependence of chain oxygen ordering in the same crystals observed by hard X-ray diffraction. The stability of the photo-induced state is in agreement with reported persistent photo-induced superconductivity effects. (C) 2000 Elsevier Science B.V. All rights reserved.
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| 5. |
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| 6. |
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| 7. |
- Petrykin, V., Kakihana, M., Tanaka,Y., Yasuoka, H., Abe, M. and Eriksson, S.
(författare)
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Ferromagnetic and superconducting properties of pure RuCe0.5Eu1.5Sr2Cu2O10 samples prepared by polymerizable complex method
- 2002
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Ingår i: Physica. ; C 378-381, s. 47-
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Tidskriftsartikel (refereegranskat)
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| 8. |
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| 9. |
- Frantti, J., Ivanov,S. A., Eriksson, .S- G. Rundlöf, H. Lantto, V. Lappalainen, J. and Kakihana, M.
(författare)
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High resolution neutron powder diffraction study of the microstrain contributions in Pb(ZrxTi1
- 2002
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Ingår i: Proceeding at the Electroceramics VIII Conference, August 25-28 2002, Rome, Italy.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 10. |
- Frantti, J., Ivanov, S. A., Eriksson, S.- G., Rundlöf, H., Lantto,V.Lappalainen, J. and Kakihana, M.
(författare)
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On the phase transitions of Pb(ZrxTi1
- 2002
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Ingår i: Phys. Rev.. ; B66, s. 64108-
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Tidskriftsartikel (refereegranskat)
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| 11. |
- Frantti, J., Ivanov, S., Eriksson, S.- G., Lappalainen, J., Lantto, V. and Kakihana, M.
(författare)
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Neutron Diffraction and Bond-valence Calulation studies of Pb(ZrxTi1
- 2002
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Ingår i: Ferroelectrics. ; 272, s. 51-
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Tidskriftsartikel (refereegranskat)
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| 12. |
- Frantti, J., Ivanov, S., Eriksson, S., Rundlöf, H., Lantto, V., Lappalainen, J. and Kakihana, M.
(författare)
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Phase transitions of Pb(ZrxTi1
- 2002
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Ingår i: Phys. Rev.. ; B66, s. 64108-
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Tidskriftsartikel (refereegranskat)
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| 13. |
- Frantti, J., Ivanov S., Lappalainen, J., Eriksson, S., Lantto, V., Nishio, S., Kakihana, M. and Rundlöf, H.
(författare)
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Local and average structure of lead titanate based ceramics
- 2002
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Ingår i: Ferroelectrics. ; 266, s. 73-
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Tidskriftsartikel (refereegranskat)
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| 14. |
- Frantti, J, et al.
(författare)
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Local and average structure of lead titanate based ceramics
- 2002
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Ingår i: Ferroelectrics. - : Informa UK Limited. - 0015-0193 .- 1563-5112. ; 266:1, s. 73-90
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Tidskriftsartikel (refereegranskat)abstract
- The revised lattice dynamics of Pb(Zr x Ti 1 -x )O 3 (PZT) with 0.10 ≤ x ≤0.54 ceramics is reported. The phase transition from tetragonal phase to the monoclinic phase is proposed to occur via locally distorted regions. Neutron diffraction data suggests that these local regions transform to the monoclinic phase with decreasing temperature, when x ≈0.50.
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| 15. |
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| 16. |
- Frantti, J, et al.
(författare)
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Neutron diffraction studies of Pb(ZrxTi1-x)O-3 ceramics
- 2000
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Ingår i: JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS. - : INST PURE APPLIED PHYSICS. - 0021-4922. ; 39:9B, s. 5697-5703
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Tidskriftsartikel (refereegranskat)abstract
- Neutron diffraction studies of lead zirconate titanate Pb(ZrxT1-x)O-3 (PZT) powders, 0.20 less than or equal to x less than or equal to 0.54, were carried out at 10 K and 297 K, The phase transition predicted by our earlier Raman observations (J. Frantti,
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| 17. |
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| 18. |
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