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  • 1.
    Ahmadi, Sareh
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Agnarsson, Björn
    Bidermane, Ieva
    Wojek, Bastian M.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Noël, Quentin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Sun, Chenghua
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Site-dependent charge transfer at the Pt(111)-ZnPc interface and the effect of iodine2014Ingår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 140, nr 17, s. 174702-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electronic structure of ZnPc, from sub-monolayers to thick films, on bare and iodated Pt(111) is studied by means of X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and scanning tunneling microscopy. Our results suggest that at low coverage ZnPc lies almost parallel to the Pt(111) substrate, in a non-planar configuration induced by Zn-Pt attraction, leading to an inhomogeneous charge distribution within the molecule and an inhomogeneous charge transfer to the molecule. ZnPc does not form a complete monolayer on the Pt surface, due to a surface-mediated intermolecular repulsion. At higher coverage ZnPc adopts a tilted geometry, due to a reduced molecule-substrate interaction. Our photoemission results illustrate that ZnPc is practically decoupled from Pt, already from the second layer. Pre-deposition of iodine on Pt hinders the Zn-Pt attraction, leading to a non-distorted first layer ZnPc in contact with Pt(111)-I(root 3x root 3) or Pt(111)-I(root 7x root 7), and a more homogeneous charge distribution and charge transfer at the interface. On increased ZnPc thickness iodine is dissolved in the organic film where it acts as an electron acceptor dopant.

  • 2.
    Ahmadi, Sareh
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Agnarsson, Björn
    Bidermane, Leva
    Wojek, Bastian M.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Noël, Quentin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Sun, Chenghua
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Effect of the iodineon the site-dependent charge transfer at the Pt(111)-ZnPc interfaceManuskript (preprint) (Övrigt vetenskapligt)
  • 3.
    Berntsen, Magnus H.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Götberg, Olof
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Wojek, Bastian M.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Tjernberg, Oscar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Direct observation of decoupled Dirac states at the interface between topological and normal insulators2013Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 88, nr 19, artikel-id 195132Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Several proposed applications and exotic effects in topological insulators rely on the presence of helical Dirac states at the interface between a topological insulator and a normal insulator. In the present work, we have used low-energy angle-resolved photoelectron spectroscopy to uncover and characterize the interface states of Bi2Se3 thin films and Bi2Te3/Bi2Se3 heterostructures grown on Si(111). The results establish that Dirac fermions are indeed present at the topological-normal-insulator boundary and absent at the topological-topological-insulator interface. Moreover, it is demonstrated that band bending present within the topological-insulator films leads to a substantial separation of the interface and surface states in energy. These results pave the way for further studies and the realization of interface-related phenomena in topological-insulator thin-film heterostructures.

  • 4. Dziawa, P.
    et al.
    Kowalski, B. J.
    Dybko, K.
    Buczko, R.
    Szczerbakow, A.
    Szot, M.
    Lusakowska, E.
    Balasubramanian, T.
    Wojek, Bastian M.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Materialfysik, MF (Stängd 20120101).
    Hårdensson Berntsen, Magnus
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Materialfysik, MF (Stängd 20120101).
    Tjernberg, Oscar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Materialfysik, MF (Stängd 20120101).
    Story, T.
    Topological crystalline insulator states in Pb1-xSnxSe2012Ingår i: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 11, nr 12, s. 1023-1027Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Topological insulators are a class of quantum materials in which time-reversal symmetry, relativistic effects and an inverted band structure result in the occurrence of electronic metallic states on the surfaces of insulating bulk crystals. These helical states exhibit a Dirac-like energy dispersion across the bulk bandgap, and they are topologically protected. Recent theoretical results have suggested the existence of topological crystalline insulators (TCIs), a class of topological insulators in which crystalline symmetry replaces the role of time-reversal symmetry in ensuring topological protection(1,2). In this study we show that the narrow-gap semiconductor Pb1-xSnxSe is a TCI for x = 0.23. Temperature-dependent angle-resolved photoelectron spectroscopy demonstrates that the material undergoes a temperature-driven topological phase transition from a trivial insulator to a TCI. These experimental findings add a new class to the family of topological insulators, and we anticipate that they will lead to a considerable body of further research as well as detailed studies of topological phase transitions.

  • 5.
    Kozhevnikov, V.
    et al.
    Tulsa Community College, Tulsa, Oklahoma 74119, USA.
    Suter, A.
    Paul Scherrer Institute, 5232 Villigen PSI, Switzerland.
    Fritzsche, H.
    Canadian Neutron Beam Centre, National Research Council Canada, Chalk River Laboratories, Ontario, Canada K0J1J0.
    Gladilin, V.
    TQC, Universiteit Antwerpen, 2610 Antwerpen, Belgium.
    Volodin, A.
    Laboratory of Solid-State Physics and Magnetism, KU Leuven, 3001 Leuven, Belgium.
    Moorkens, T.
    Laboratory of Solid-State Physics and Magnetism, KU Leuven, 3001 Leuven, Belgium.
    Trekels, M.
    Institute for Nuclear and Radiation Physics, KU Leuven, 3001 Leuven, Belgium.
    Cuppens, J.
    Laboratory of Solid-State Physics and Magnetism, KU Leuven, 3001 Leuven, Belgium.
    Wojek, Bastian M.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF. Paul Scherrer Institute.
    Prokscha, T.
    Paul Scherrer Institute, 5232 Villigen PSI, Switzerland.
    Morenzoni, E.
    Paul Scherrer Institute, 5232 Villigen PSI, Switzerland.
    Nieuwenhuys, G. J.
    Paul Scherrer Institute, 5232 Villigen PSI, Switzerland.
    Van Bael, M. J.
    Laboratory of Solid-State Physics and Magnetism, KU Leuven, 3001 Leuven, Belgium.
    Temst, K.
    Institute for Nuclear and Radiation Physics, KU Leuven, 3001 Leuven, Belgium.
    Van Haesendonck, C.
    Laboratory of Solid-State Physics and Magnetism, KU Leuven, 3001 Leuven, Belgium.
    Indekeu, J. O.
    Institute for Theoretical Physics, KU Leuven, 3001 Leuven, Belgium.
    Nonlocal effect and dimensions of Cooper pairs measured by low-energy muons and polarized neutrons in type-I superconductors2013Ingår i: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 87, nr 10, s. 104508-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Pippard coherence length xi(0) (the size of a Cooper pair) in two extreme type-I superconductors (In and Sn) was determined directly through high-resolution measurement of the nonlocal electrodynamic effect combining low-energy muon spin rotation spectroscopy and polarized neutron reflectometry. The renormalization factor Z = m*(cp)/2m (m*(cp) and m are the mass of the Cooper pair and the electron, respectively) resulting from the electron-phonon interaction, and the temperature-dependent London penetration depth lambda(L)(T) were determined as well. An expression linking xi(0), Z, and lambda(L)(0) is introduced and experimentally verified. This expression allows one to determine experimentally the Pippard coherence length in any superconductor, independent of whether the superconductor is local or nonlocal, conventional or unconventional.

  • 6. Morenzoni, Elvezio
    et al.
    Prokscha, Thomas
    Saadaoui, Hassan
    Salman, Zaher
    Suter, Andreas
    Wojek, Bastian M.
    Paul Scherrer Institut, Switzerland; Universität Zürich, Switzerland.
    Baglo, Jordan
    Božović, Ivan
    Hossain, Masrur
    Kiefl, Robert F.
    Logvenov, Gennady
    Ofer, Oren
    Low-Energy Muons at PSI: Examples of Investigations of Superconducting Properties in Near-Surface Regions and Heterostuctures2014Ingår i: Proceedings of the International Symposium on Science Explored by Ultra Slow Muon (USM2013), The Physical Society of Japan , 2014, Vol. 2, artikel-id 010201Konferensbidrag (Refereegranskat)
    Abstract [en]

    With the advent of polarized low-energy muons, with tunable energy in the kiloelectronvolt range, it is possible to use the sensitivity and the local-probe character of µSR to perform depth-dependent investigations on the nanometer scale of magnetic and superconducting properties of materials. Here, after a brief summary of the present status of LE-µSR at PSI, we give some examples of investigations of superconducting properties in the near-surface regions of single crystals and thin-film materials.

  • 7. Ofer, O.
    et al.
    Baglo, J. C.
    Hossain, M. D.
    Kiefl, R. F.
    Hardy, W. N.
    Thaler, A.
    Kim, H.
    Tanatar, M. A.
    Canfield, P. C.
    Prozorov, R.
    Luke, G. M.
    Morenzoni, E.
    Saadaoui, H.
    Suter, A.
    Prokscha, T.
    Wojek, Bastian M.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Materialfysik, MF (Stängd 20120101).
    Salman, Z.
    Absolute value and temperature dependence of the magnetic penetration depth in Ba(Co 0.074Fe 0.926) 2As 22012Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 85, nr 6, s. 060506-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The absolute value and temperature dependence of the in-plane magnetic penetration depth lambda have been measured on a single crystal of Ba(Co0.074Fe0.926)(2)As-2 using low-energy muon-spin rotation and microwave cavity perturbation. The magnetic field profiles in the Meissner state are consistent with a local London model beyond a depth of 15 nm. We determine the gap symmetry through measurements of the temperature dependence of the superfluid density which follows a two-gap s-wave model over the entire temperature range below T-c. While the intermediate to high temperature data is well fit by an energy gap model in the BCS-like (weak-coupling) limit, a second smaller gap becomes apparent at low temperatures.

  • 8. Polley, C. M.
    et al.
    Dziawa, P.
    Reszka, A.
    Szczerbakow, A.
    Minikayev, R.
    Domagala, J. Z.
    Safaei, S.
    Kacman, P.
    Buczko, R.
    Adell, J.
    Hårdensson Berntsen, Magnus
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Wojek, Bastian M.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Tjernberg, Oscar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Kowalski, B. J.
    Story, T.
    Balasubramanian, T.
    Observation of topological crystalline insulator surface states on (111)-oriented Pb1-xSnxSe films2014Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 89, nr 7, s. 075317-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present angle-resolved photoemission spectroscopy measurements of the surface states on in-situ grown (111) oriented films of Pb1-xSnxSe, a three-dimensional topological crystalline insulator. We observe surface states with Dirac-like dispersion at (Gamma) over bar and (M) over bar in the surface Brillouin zone, supporting recent theoretical predictions for this family of materials. We study the parallel dispersion isotropy and Dirac-point binding energy of the surface states, and perform tight-binding calculations to support our findings. The relative simplicity of the growth technique is encouraging, and suggests a clear path for future investigations into the role of strain, vicinality, and alternative surface orientations in (Pb,Sn)Se solid solutions.

  • 9.
    Stilp, E.
    et al.
    Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, Switzerland.
    Suter, A.
    Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, Switzerland.
    Prokscha, T.
    Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, Switzerland.
    Morenzoni, E.
    Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, Switzerland.
    Keller, H.
    Physik-Institut der Universität Zürich, Switzerland.
    Wojek, Bastian M.
    Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, Switzerland; Physik-Institut der Universität Zurich, Switzerland.
    Luetkens, H.
    Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, Switzerland.
    Gozar, A.
    Brookhaven National Laboratory, New York, USA.
    Logvenov, G.
    Max Planck Institute for Solid State Research, Stuttgart, Germany..
    Božović, I.
    Brookhaven National Laboratory, New York, USA.
    Magnetic phase diagram of low-doped La2-xSrxCuO4 thin films studied by low-energy muon-spin rotation2013Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 88, nr 6, s. 064419-1-064419-11, artikel-id 064419Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The magnetic phase diagram of La2-xSrxCuO4 thin films grown on single-crystal LaSrAlO4 substrates has been determined by low-energy muon-spin rotation. The diagram shows the same features as the one of bulk La2-xSrxCuO4, but the transition temperatures between distinct magnetic states are significantly different. In the antiferromagnetic phase the Neel temperature T-N is strongly reduced, and no hole spin freezing is observed at low temperatures. In the disordered magnetic phase (x greater than or similar to 0.02) the transition temperature to the cluster spin-glass state T-g is enhanced. Possible reasons for the pronounced differences between the magnetic phase diagrams of thin-film and bulk samples are discussed.

  • 10. Suter, Andreas
    et al.
    Morenzoni, Elvezio
    Prokscha, Thomas
    Wojek, Bastian M.
    Universität Zürich, Switzerland; Paul Scherrer Institut, Switzerland.
    Luetkens, Hubertus
    Gozar, Adrian
    Logvenov, Gennady
    Božović, Ivan
    Two-Dimensional Magnetic and Superconducting Phases in Metal-Insulator La2−xSrxCuO4 Superlattices Studied by Low-Energy Muon-Spin Rotation2014Ingår i: Proceedings of the International Symposium on Science Explored by Ultra Slow Muon (USM2013), Physical society of Japan, 2014, Vol. 2, s. 010204-010204, artikel-id 010204Konferensbidrag (Refereegranskat)
    Abstract [en]

    We show, by means of low-energy muon-spin-rotation measurements, that few-unit-cells thick La2CuO4 layers synthesized digitally by molecular beam epitaxy are antiferromagnetically ordered. Below a thickness of about 5 CuO2 layers the long-range ordered state breaks down, and a magnetic state appears with enhanced quantum fluctuations and a reduced spin stiffness. This magnetic state can exist in close proximity (few Å) to high-temperature superconducting layers, without transmitting supercurrents. Charge-transfer effects and potential softening of the antiferromagnetic state due to the proximity to the superconducting state are discussed.

  • 11.
    Wojek, Bastian M.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Comment on "Probing two- and three-dimensional electrons in MgB2 with soft x-ray angle-resolved photoemission"Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    A recent article by Sassa et al. [Phys. Rev. B 91, 045114 (2015)] reports on a soft-xray angle-resolved photoemission study of MgB2. The analysis and/or presentation of the collected data and the corresponding calculations appear to be partially inconsistent. The aim of this comment is to provide a guide to these inconsistencies and to discuss their influence on the presented conclusions.

  • 12.
    Wojek, Bastian M.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Materialfysik, MF (Stängd 20120101).
    Buczko, R.
    Safaei, S.
    Dziawa, P.
    Kowalski, B. J.
    Hårdensson Berntsen, Magnus
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Materialfysik, MF (Stängd 20120101).
    Balasubramanian, T.
    Leandersson, M.
    Szczerbakow, A.
    Kacman, P.
    Story, T.
    Tjernberg, Oscar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Materialfysik, MF (Stängd 20120101).
    Spin-polarized (001) surface states of the topological crystalline insulator Pb0.73Sn0.27Se2013Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 87, nr 11, s. 115106-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the nature of (001) surface states in Pb0.73Sn0.27Se in the newly discovered topological-crystalline-insulator (TCI) phase as well as the corresponding topologically trivial state above the band-gap-inversion temperature. Our calculations predict not only metallic surface states with a nontrivial chiral spin structure for the TCI case, but also nonmetallic (gapped) surface states with nonzero spin polarization when the system is a normal insulator. For both phases, angle- and spin-resolved photoelectron spectroscopy measurements provide conclusive evidence for the formation of these (001) surface states in Pb0.73Sn0.27Se, as well as for their chiral spin structure.

  • 13.
    Wojek, Bastian M.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Dziawa, P.
    Kowalski, B. J.
    Szczerbakow, A.
    Black-Schaffer, A. M.
    Hårdensson Berntsen, Magnus
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Balasubramanian, T.
    Story, T.
    Tjernberg, Oskar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Band inversion and the topological phase transition in (Pb,Sn)Se2014Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 90, nr 16, s. 161202-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The recent discovery of a topological phase transition in IV-VI narrow-gap semiconductors has revitalized the decades-old interest in the bulk band inversion occurring in these materials. Here we systematically study the (001) surface states of Pb1-xSnxSe mixed crystals by means of angle-resolved photoelectron spectroscopy in the parameter space 0 <= x <= 0.37 and 300 K >= T >= 9 K. Using the surface-state observations, we monitor directly the topological phase transition in this solid solution and gain valuable information on the evolution of the underlying fundamental band gap of the system. In contrast to common model expectations, the band-gap evolution appears to be nonlinear as a function of the studied parameters, resulting in the measuring of a discontinuous band-inversion process. This finding signifies that the anticipated gapless bulk state is in fact not a stable configuration and that the topological phase transition therefore exhibits features akin to a first-order transition.

  • 14.
    Wojek, Bastian M.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Hårdensson Berntsen, M.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Jonsson, Viktor
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF. KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Szczerbakow, A.
    Dziawa, P.
    Kowalski, B. J.
    Story, T.
    Tjernberg, Oscar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF. KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Direct observation and temperature control of the surface Dirac gap in a topological crystalline insulator2015Ingår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, artikel-id 8463Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Since the advent of topological insulators hosting Dirac surface states, efforts have been made to gap these states in a controllable way. A new route to accomplish this was opened up by the discovery of topological crystalline insulators where the topological states are protected by crystal symmetries and thus prone to gap formation by structural changes of the lattice. Here we show a temperature-driven gap opening in Dirac surface states within the topological crystalline insulator phase in (Pb,Sn) Se. By using angle-resolved photoelectron spectroscopy, the gap formation and mass acquisition is studied as a function of composition and temperature. The resulting observations lead to the addition of a temperature-and composition-dependent boundary between massless and massive Dirac states in the topological phase diagram for (Pb,Sn) Se (001). Overall, our results experimentally establish the possibility to tune between massless and massive topological states on the surface of a topological system.

  • 15.
    Wojek, Bastian M.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Materialfysik, MF (Stängd 20120101).
    Hårdensson Berntsen, Magnus
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Materialfysik, MF (Stängd 20120101).
    Boseggia, S.
    Boothroyd, A. T.
    Prabhakaran, D.
    McMorrow, D. F.
    Ronnow, H. M.
    Chang, J.
    Tjernberg, Oscar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik (Stängd 20120101), Materialfysik, MF (Stängd 20120101).
    The J(eff)=1/2 insulator Sr3Ir2O7 studied by means of angle-resolved photoemission spectroscopy2012Ingår i: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 24, nr 41, s. 415602-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The low-energy electronic structure of the J(eff) = 1/2 spin-orbit insulator Sr3Ir2O7 has been studied by means of angle-resolved photoemission spectroscopy. A comparison of the results for bilayer Sr3Ir2O7 with available literature data for the related single-layer compound Sr2IrO4 reveals qualitative similarities and similar J(eff) = 1/2 bandwidths for the two materials, but also pronounced differences in the distribution of the spectral weight. In particular, photoemission from the J(eff) = 1/2 states appears to be suppressed. Yet, it is found that the Sr3Ir2O7 data are in overall better agreement with band-structure calculations than the data for Sr2IrO4.

  • 16.
    Wojek, Bastian M.
    et al.
    Univ Zurich.
    Morenzoni, E.
    Eshchenko, D. G.
    Suter, A.
    Prokscha, T.
    Keller, H.
    Koller, E.
    Fischer, O.
    Malik, V. K.
    Bernhard, C.
    Doebeli, M.
    Magnetism, superconductivity, and coupling in cuprate heterostructures probed by low-energy muon-spin rotation2012Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 85, nr 2, s. 024505-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a low-energy muon-spin-rotation study of the magnetic and superconducting properties of YBa(2)Cu(3)O(7-delta)/PrBa(2)Cu(3)O(7-delta) trilayer and bilayer heterostructures. By determining the magnetic-field profiles throughout these structures, we show that a finite superfluid density can be induced in otherwise semiconducting PrBa(2)Cu(3)O(7-delta) layers when juxtaposed to YBa(2)Cu(3)O(7-delta) "electrodes," while the intrinsic antiferromagnetic order is unaffected.

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