Change search
Link to record
Permanent link

Direct link
Katterwe, Sven Olof
Alternative names
Publications (10 of 17) Show all publications
Jacobs, T., Katterwe, S.-O. & Krasnov, V. M. (2016). Superconducting correlations above T-c in the pseudogap state of Bi2Sr2CaCu2O8+delta cuprates revealed by angular-dependent magnetotunneling. Physical Review B, 94(22), Article ID 220501.
Open this publication in new window or tab >>Superconducting correlations above T-c in the pseudogap state of Bi2Sr2CaCu2O8+delta cuprates revealed by angular-dependent magnetotunneling
2016 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 94, no 22, article id 220501Article in journal (Refereed) Published
Abstract [en]

We present an angular-dependent magnetotunneling technique, which facilitates unambiguous separation of superconducting (supporting circulating screening currents) and nonsuperconducting (not supporting screening currents) contributions to the pseudogap phenomenon in layered Bi2Sr2CaCu2O8+delta cuprates. Our data indicate persistence of superconducting correlations at temperatures up to 1.5T(c) in a form of both phase and amplitude fluctuations of the superconducting order parameter. However, despite a profound fluctuations region, only a small fraction of the pseudogap spectrum is caused by superconducting correlations, while the dominating part comes from a competing nonsuperconducting order, which does not support circulating orbital currents.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-137571 (URN)10.1103/PhysRevB.94.220501 (DOI)000389502500001 ()2-s2.0-85002244995 (Scopus ID)
Available from: 2017-01-11 Created: 2017-01-09 Last updated: 2022-10-18Bibliographically approved
Katterwe, S. O., Jacobs, T., Maljuk, A. & Krasnov, V. M. (2014). Low anisotropy of the upper critical field in a strongly anisotropic layered cuprate Bi2.15Sr1.9CuO6+δ: Evidence for a paramagnetically limited superconductivity. Physical Review B, 89(21), Article ID 214516.
Open this publication in new window or tab >>Low anisotropy of the upper critical field in a strongly anisotropic layered cuprate Bi2.15Sr1.9CuO6+δ: Evidence for a paramagnetically limited superconductivity
2014 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 89, no 21, article id 214516Article in journal (Refereed) Published
Abstract [en]

We study angular-dependent magnetoresistance in a low-T-c layered cuprate Bi2.15Sr1.9CuO6+delta. The low Tc similar to 4 K allows complete suppression of superconductivity by modest magnetic fields and facilitates accurate analysis of the upper critical field H-c2. We observe a universal exponential decay of fluctuation conductivity in a broad range of temperatures above Tc and propose a method for extraction of H-c2(T) from the scaling analysis of the fluctuation conductivity at T > T c. Our main result is observation of a surprisingly low H-c2 anisotropy similar to 2, which is much smaller than the effective mass anisotropy of the material similar to 300. We show that the anisotropy is decreasing with increasing field and saturates at a small value when the field reaches the paramagnetic limit. We argue that the dramatic discrepancy of high-field and low-field anisotropies is clear evidence for paramagnetically limited superconductivity.

National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-106332 (URN)10.1103/PhysRevB.89.214516 (DOI)000337943500005 ()2-s2.0-84903511929 (Scopus ID)
Note

AuthorCount:4;

Available from: 2014-08-07 Created: 2014-08-04 Last updated: 2022-10-12Bibliographically approved
Krasnov, V. M., Katterwe, S.-O. & Rydh, A. (2013). Signatures of the electronic nature of pairing in high-T-c superconductors obtained by non-equilibrium boson spectroscopy. Nature Communications, 4, Article ID 2970.
Open this publication in new window or tab >>Signatures of the electronic nature of pairing in high-T-c superconductors obtained by non-equilibrium boson spectroscopy
2013 (English)In: Nature Communications, E-ISSN 2041-1723, Vol. 4, article id 2970Article in journal (Refereed) Published
Abstract [en]

Understanding the pairing mechanism that gives rise to high-temperature superconductivity is one of the longest-standing problems of condensed-matter physics. Almost three decades after its discovery, even the question of whether or not phonons are involved remains a point of contention to some. Here we describe a technique for determining the spectra of bosons generated during the formation of Cooper pairs on recombination of hot electrons as they tunnel between the layers of a cuprate superconductor. The results obtained indicate that the bosons that mediate pairing decay over micrometre-scale distances and picosecond timescales, implying that they propagate at a speed of around 106 m s−1. This value is more than two orders of magnitude greater than the phonon propagation speed but close to Fermi velocity for electrons, suggesting that the pairing mechanism is mediated by unconventional repulsive electron–electron, rather than attractive electron–phonon, interactions. 

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:su:diva-100397 (URN)10.1038/ncomms3970 (DOI)000329397600006 ()2-s2.0-84890735554 (Scopus ID)
Funder
Swedish Research Council
Note

AuthorCount:3;

Available from: 2014-02-03 Created: 2014-02-03 Last updated: 2023-03-28Bibliographically approved
Motzkau, H., Katterwe, S.-O., Rydh, A. & Krasnov, V. M. (2013). Strong polaritonic interaction between flux-flow and phonon resonances in Bi2Sr2CaCu2O8+x intrinsic Josephson junctions: Angular dependence and the alignment procedure. Physica. C, Superconductivity, 491, 51-55
Open this publication in new window or tab >>Strong polaritonic interaction between flux-flow and phonon resonances in Bi2Sr2CaCu2O8+x intrinsic Josephson junctions: Angular dependence and the alignment procedure
2013 (English)In: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 491, p. 51-55Article in journal (Refereed) Published
Abstract [en]

Bi2Sr2CaCu2O8+x single crystals represent natural stacks of atomic scale intrinsic Josephson junctions, formed between metallic CuO2–Ca–CuO2 and ionic insulating SrO–2BiO–SrO layers. Electrostriction effect in the insulating layers leads to excitation of c-axis phonons by the ac-Josephson effect. Here we study experimentally the interplay between and velocity matching (Eck) electromagnetic resonances in the flux-flow state of small mesa structures with c-axis optical phonons. A very strong interaction is reported, which leads to formation of phonon-polaritons with infrared and Raman-active transverse optical phonons. A special focus in this work is made on analysis of the angular dependence of the resonances. We describe an accurate sample alignment procedure that prevents intrusion of Abrikosov vortices in fields up to 17 T, which is essential for achieving high-quality resonances at record high frequencies up to 13 THz.

Keywords
Bi-based cuprates, Intrinsic Josephson junctions
National Category
Condensed Matter Physics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-89384 (URN)10.1016/j.physc.2012.11.001 (DOI)000320597700013 ()
Available from: 2013-04-23 Created: 2013-04-23 Last updated: 2022-02-24Bibliographically approved
Jacobs, T., Katterwe, S. O., Motzkau, H., Rydh, A., Maljuk, A., Helm, T., . . . Krasnov, V. . (2012). Electron-tunneling measurements of low-T-c single-layer Bi2+xSr2-yCuO6+delta: Evidence for a scaling disparity between superconducting and pseudogap states. Physical Review B, 86(21), Article ID 214506.
Open this publication in new window or tab >>Electron-tunneling measurements of low-T-c single-layer Bi2+xSr2-yCuO6+delta: Evidence for a scaling disparity between superconducting and pseudogap states
Show others...
2012 (English)In: Physical Review B, ISSN 2469-9950, Vol. 86, no 21, article id 214506Article in journal (Refereed) Published
Abstract [en]

We experimentally study intrinsic tunneling and high magnetic field (up to 65 T) transport characteristics of the single-layer cuprate Bi2+xSr2-yCuO6+delta, with a very low superconducting critical temperature T-c less than or similar to 4 K. It is observed that the superconducting gap, the collective bosonic mode energy, the upper critical field, and the fluctuation temperature range are scaling down with T-c, while the corresponding pseudogap characteristics remain the same as in high-T-c cuprates with 20 to 30 times higher T-c. The observed disparity of the superconducting and pseudogap scales clearly reveals their different origins.

National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-86498 (URN)10.1103/PhysRevB.86.214506 (DOI)000312290600002 ()2-s2.0-84871071245 (Scopus ID)
Note

AuthorCount:10;

Available from: 2013-01-14 Created: 2013-01-14 Last updated: 2022-09-30Bibliographically approved
Motzkau, H., Jacobs, T., Katterwe, S.-O., Rydh, A. & Krasnov, V. M. (2012). Persistent electrical doping of Bi2Sr2CaCu2O8+x mesa structures. Physical Review B, 85(14), Article ID 144519.
Open this publication in new window or tab >>Persistent electrical doping of Bi2Sr2CaCu2O8+x mesa structures
Show others...
2012 (English)In: Physical Review B, ISSN 2469-9950, Vol. 85, no 14, article id 144519Article in journal (Refereed) Published
Abstract [en]

Application of a significantly large bias voltage to small Bi2Sr2CaCu2O8+x mesa structures leads to persistent doping of the mesas. Here, we employ this effect for analysis of the doping dependence of the electronic spectra of Bi-2212 single crystals by means of intrinsic tunneling spectroscopy. We are able to controllably and reversibly change the doping state of the same single crystal from underdoped to overdoped state, without changing its chemical composition. It is observed that such physical doping is affecting superconductivity in Bi-2212 similar to chemical doping by oxygen impurities: with overdoping, the critical temperature and the superconducting gap decrease; with underdoping, the c-axis critical current rapidly decreases due to progressively more incoherent interlayer tunneling and the pseudogap rapidly increases, indicative for the presence of the critical doping point. We distinguish two main mechanisms of persistent electric doping: (i) even-in-voltage contribution, attributed to a charge transfer effect, and (ii) odd-in-voltage contribution, attributed to reordering of oxygen vacancies.

National Category
Condensed Matter Physics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-80276 (URN)10.1103/PhysRevB.85.144519 (DOI)000302958900003 ()2-s2.0-84860266637 (Scopus ID)
Note

AuthorCount:5;

Available from: 2012-09-27 Created: 2012-09-17 Last updated: 2022-10-03Bibliographically approved
Motzkau, H., Katterwe, S.-O., Rydh, A. & Krasnov, V. M. (2012). Size-dependent transformation from triangular to rectangular fluxon lattice in Bi-2212 mesa structures. In: 26th International Conference on Low Temperature Physics (LT26): . Paper presented at 26th International Conference on Low Temperature Physics (LT26), Beijing, Peoples Republic of China, August 10-17, 2011. Institute of Physics (IOP), Article ID 052022.
Open this publication in new window or tab >>Size-dependent transformation from triangular to rectangular fluxon lattice in Bi-2212 mesa structures
2012 (English)In: 26th International Conference on Low Temperature Physics (LT26), Institute of Physics (IOP), 2012, article id 052022Conference paper, Published paper (Refereed)
Abstract [en]

We present a systematic study of the field and size dependencies of the static fluxon lattice configuration in Bi-2212 intrinsic Josephson junctions and investigate conditions needed for the formation of a rectangular fluxon lattice required for a high power flux-flow oscillator. We fabricate junctions of different sizes from Bi2Sr2CaCu2O8+x and Bi1.75Pb0.25Sr2CaCu2O8+xsingle crystals using the mesa technique and study the Fraunhofer-like modulation of the critical current with magnetic field. The modulation can be divided into three regions depending on the formed fluxon lattice. At low field, no periodic modulation and no ordered fluxon lattice is found. At intermediate fields, modulation with half-flux quantum periodicity due to a triangular lattice is seen. At high fields, the rectangular lattice gives integer flux quantum periodicity. We present these fields in dependence on the sample size and conclude that the transitions between the regions depend only on λJ(Jc) and occur at about 0.4 and 1.3 fluxons per λJ, respectively. These numbers are universal for the measured samples and are consistent with performed numerical simulations.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2012
Series
Journal of Physics Conference Series, ISSN 1742-6588, E-ISSN 1742-6596 ; 400
National Category
Condensed Matter Physics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-89383 (URN)10.1088/1742-6596/400/5/052022 (DOI)000314977100461 ()
Conference
26th International Conference on Low Temperature Physics (LT26), Beijing, Peoples Republic of China, August 10-17, 2011
Available from: 2013-04-23 Created: 2013-04-23 Last updated: 2022-02-24Bibliographically approved
Katterwe, S.-O., Motzkau, H., Rydh, A. & Krasnov, V. M. (2011). Coherent generation of phonon-polaritons in Bi2Sr2CaCu2O8+x intrinsic Josephson junctions. Physical Review B Condensed Matter, 83(10), Article ID 100510.
Open this publication in new window or tab >>Coherent generation of phonon-polaritons in Bi2Sr2CaCu2O8+x intrinsic Josephson junctions
2011 (English)In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 83, no 10, article id 100510Article in journal (Refereed) Published
Abstract [en]

The Bi2Sr2CaCu2O8+x high-temperature superconductor represents a natural layered metamaterial composed of metallic CuO bilayers sandwiched between ionic BiO planes. Each pair of CuO bilayers forms an atomic-scale Josephson junction. Here we employ the intrinsic Josephson effect for in situ generation and self-detection of electromagnetic waves in Bi2Sr2CaCu2O8+x single crystals. We observe that electromagnetic waves form polaritons with several transverse optical phonons. This indicates the presence of unscreened polar response in cuprates, which may lead to unusually strong electron-phonon interaction. Our technique can provide intense local sources of coherent, monochromatic phonon-polaritons with kW/cm2 power densities.

National Category
Condensed Matter Physics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-62392 (URN)10.1103/PhysRevB.83.100510 (DOI)000288510800001 ()
Available from: 2011-09-16 Created: 2011-09-16 Last updated: 2022-02-24Bibliographically approved
Krasnov, V. M., Motzkau, H., Golod, T., Rydh, A., Katterwe, S.-O. & Kulakov, A. B. (2011). Comparative analysis of tunneling magnetoresistance in low-Tc Nb/Al-AlOx/Nb and high-Tc Bi2−yPbySr2CaCu2O8+δ intrinsic Josephson junctions. Physical Review B Condensed Matter, 84(5), Article ID 054516.
Open this publication in new window or tab >>Comparative analysis of tunneling magnetoresistance in low-Tc Nb/Al-AlOx/Nb and high-Tc Bi2−yPbySr2CaCu2O8+δ intrinsic Josephson junctions
Show others...
2011 (English)In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 84, no 5, article id 054516Article in journal (Refereed) Published
Abstract [en]

We perform a detailed comparison of magnetotunneling in conventional low-Tc Nb/Al-AlOx/Nb junctions with that in slightly overdoped Bi2−yPbySr2CaCu2O8+δ [Bi(Pb)-2212] intrinsic Josephson junctions and with microscopic calculations. It is found that both types of junctions behave in a qualitatively similar way. Both magnetic field and temperature suppress superconductivity in the state-conserving manner. This leads to the characteristic sign change of tunneling magnetoresistance from the negative at the subgap to the positive at the sum-gap bias. We derived theoretically and verified experimentally scaling laws of magnetotunneling characteristics and employ them for accurate extraction of the upper critical field Hc2. For Nb an extended region of surface superconductivity at Hc2<H<Hc3 is observed. The parameters of Bi(Pb)-2212 were obtained from self-consistent analysis of magnetotunneling data at different levels of bias, dissipation powers, and for different mesa sizes, which precludes the influence of self-heating. It is found that Hc2(0) for Bi(Pb)-2212 is ≃T→Tc T and decreases significantly at T→Tc. The amplitude of subgap magnetoresistance is suppressed exponentially at T>Tc/2, but remains negative, although very small, above Tc. This may indicate the existence of an extended fluctuation region, which, however, does not destroy the general second-order type of the phase transition at Tc.

National Category
Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-62397 (URN)10.1103/PhysRevB.84.054516 (DOI)000293702000010 ()
Available from: 2011-09-16 Created: 2011-09-16 Last updated: 2022-02-24Bibliographically approved
Katterwe, S.-O. (2011). Properties of small Bi2Sr2CaCu2O8 intrinsic Josephson junctions: confinement, flux-flow and resonant phenomena. (Doctoral dissertation). Stockholm: Department of Physics, Stockholm University
Open this publication in new window or tab >>Properties of small Bi2Sr2CaCu2O8 intrinsic Josephson junctions: confinement, flux-flow and resonant phenomena
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, intrinsic Josephson junctions, naturally formed in the strongly anisotropic high-temperature superconductor Bi2Sr2CaCu2O8 (Bi-2212), are studied experimentally. For this purpose, small mesa structures are fabricated on the surface of single crystals using micro- and nano-fabrication tools, focused ion beam is used to reduce the area of the mesa-structures down to ≈ 1 × 1 μm2.

The properties of charge transport across copper-oxide layers inside the mesas are studied by intrinsic tunneling spectroscopy. Temperature, bias and magnetic field dependences of current-voltage characteristics are examined.

In the main part of the thesis, the behavior of intrinsic Josephson junctions in magnetic fields B parallel to the copper-oxide planes is studied. Parallel magnetic fields penetrate the junctions in the form of Josephson vortices (fluxons). At high magnetic fields, fluxons are arranged in a regular lattice and are accelerated by a sufficient high transport current. As the fluxon lattice is moving through the mesa, it emits electromagnetic waves in the important THz frequency range. Properties of Bi-2212 mesas in this flux-flow regime are studied in this thesis.

The following new observations were made during the course of this work: a crossover from thermal activation above Tc to quantum tunneling below Tc is seen in the interlayer transport-mechanism, the Fraunhofer pattern of Ic(B) is observed clearly in Bi-2212, superluminal electromagnetic cavity resonances and phonon-polaritons are observed in Bi-2212.

It is argued that the employed technique for miniaturization of mesas and the obtained results can be useful for a better understanding of fundamental properties of high-temperature superconductors and for the realizations of coherent flux-flow oscillators and coherent phonon-polariton generators in the important THz frequency range.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2011. p. 105
Keywords
high-temperature superconductivity, intrinsic Josephson junctions, tunneling, fluxons, flux-flow oscillator, THz-emission, cavity resonances, polaritons, micro/nano-fabrication
National Category
Condensed Matter Physics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-62583 (URN)978-91-7447-358-2 (ISBN)
Public defence
2011-10-27, FB41, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 6: Manuscript. Available from: 2011-10-05 Created: 2011-09-23 Last updated: 2022-02-24Bibliographically approved
Organisations

Search in DiVA

Show all publications