V. Bisogni

Publications (37)67.25 Total impact

• Source

  Available from: M. Salluzzo

  Article: Orbital reconstruction and the two-dimensional electron gas at the LaAlO3/SrTiO3 interface.

  M Salluzzo, J C Cezar, N B Brookes, V Bisogni, G M De Luca, C Richter, S Thiel, J Mannhart, M Huijben, A Brinkman, G Rijnders, G Ghiringhelli
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  ABSTRACT: In 2004, Ohtomo and Hwang discovered that an electron gas is created at the interface between insulating LaAlO3 and SrTiO3 compounds. Here we show that the generation of a conducting electron gas is related to an orbital reconstruction occurring at the LaAlO3/SrTiO3 interface. Our results are based on extensive investigations of the electronic properties and of the orbital structure of the interface using x-ray absorption spectroscopy. In particular, we find that the degeneracy of the Ti 3d states is fully removed and that the Ti 3d xy levels become the first available states for conducting electrons.
  Physical Review Letters 05/2009; 102(16):166804. · 7.37 Impact Factor
• Article: Orbital reconstruction and two-dimensional electron gas at the LaAlO3/SrTiO3 interface

  M. Salluzzo, G. Ghiringhelli, J. C. Cezar, N. B. Brookes, V. Bisogni, G. M. De Luca, C. Richter, S Thiel, J. Mannhart, M. Huijben, A. Brinkman, G. Rijnders
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  ABSTRACT: Conventional two-dimensional electron gases are realized by engineering the interfaces between semiconducting compounds. In 2004, Ohtomo and Hwang discovered that an electron gas can be also realized at the interface between large gap insulators made of transition metal oxides [1]. This finding has generated considerable efforts to clarify the underlying microscopic mechanism. Of particular interest is the LaAlO3/SrTiO3 system, because it features especially striking properties. High carrier mobility [1], electric field tuneable superconductivity [2] and magnetic effects [3], have been found. Here we show that an orbital reconstruction is underlying the generation of the electron gas at the LaAlO3/SrTiO3 n-type interface. Our results are based on extensive investigations of the electronic properties and of the orbital structure of the interface using X-ray Absorption Spectroscopy. In particular we find that the degeneracy of the Ti 3d states is fully removed, and that the Ti 3dxy levels become the first available states for conducting electrons.
  01/2009;
• Article: Dispersion of Magnetic Excitations in the Cuprate La(2)CuO(4) and CaCuO(2) Compounds Measured Using Resonant X-Ray Scattering

  L Braicovich, L J P Ament, V Bisogni, F Forte, C Aruta, G Balestrino, N B Brookes, G M Luca, P G Medaglia, F M Granozio, M Radovic, M Salluzzo, J Brink, G Ghiringhelli
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  ABSTRACT: By resonant inelastic x-ray scattering in the soft x-ray regime we probe the dynamical multiple-spin correlations in the antiferromagnetic cuprates La(2)CuO(4) and CaCuO(2). High resolution measurements at the copper L(3) edge allow the clear observation of dispersing bimagnon excitations. Theory based on the ultrashort core-hole lifetime expansion fits the data on these coherent spin excitations without free parameters.
  Physical Review Letters 01/2009; 102(16). · 7.37 Impact Factor
• Source

  Available from: M. Salluzzo

  Article: Dispersion of Magnetic Excitations in the Cuprate La(2)CuO(4) and CaCuO(2) Compounds Measured Using Resonant X-Ray Scattering

  L. Braicovich, L. J. P. Ament, V. Bisogni, F. Forte, C. Aruta, G. Balestrino, N. B. Brookes, G. M. Luca, P. G. Medaglia, F. M. Granozio, M. Radovic, M. Salluzzo, J. van den Brink, G. Ghiringhelli
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  ABSTRACT: Braicovich, L. Ament, L. J. P. Bisogni, V. Forte, F. Aruta, C. Balestrino, G. Brookes, N. B. De Luca, G. M. Medaglia, P. G. Granozio, F. Miletto Radovic, M. Salluzzo, M. van den Brink, J. Ghiringhelli, G.
  Physical Review Letters. 01/2009; 102.
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  Available from: M. Salluzzo

  Article: Dispersing bimagnons and doping induced bimagnon-charge modes in superconducting cuprates

  L. Braicovich, L. J. P. Ament, V. Bisogni, F. Forte, C. Aruta, G. Balestrino, N. B. Brookes, G. M. De Luca, P. G. Medaglia, F. Miletto Granozio, M. Radovic, M. Salluzzo, J. van den Brink, G. Ghiringhelli
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  ABSTRACT: In the early days of high temperature superconductivity it was already recognized that magnetic properties of these materials are intimately related to the superconducting ones . When doped, the long-range ordered antiferromagnetic background of pristine copper-oxide insulators melts away and makes room for a spin liquid and superconductivity. By resonant inelastic x-ray scattering (RIXS) in the soft regime we probe the hitherto inaccessible dynamical multiple-spin correlations of the magnetic background in a series of parent compounds and in high Tc materials [NCCO (Nd2-xCexCuO4) and LSCO (La2-xSrxCuO4)]. High resolution measurements allows the clear observation of dispersing bimagnon excitations. In the undoped compounds the theory, fits the data on these coherent spin excitations without free parameters. In nearly optimally doped LSCO we observe the appearance of a new collective excitation at an energy of 250 +/- 60 meV having the signature of a coupled bimagnon-charge mode. It has a strongly reduced dispersion and lies in a so far unexplored region of momentum and energy space in the mid-infrared.
  08/2008;
• Article: Evidence of orbital reconstruction at interfaces in ultrathin La0.67Sr0.33MnO3 films.

  A Tebano, C Aruta, S Sanna, P G Medaglia, G Balestrino, A A Sidorenko, R De Renzi, G Ghiringhelli, L Braicovich, V Bisogni, N B Brookes
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  ABSTRACT: Linear dichroism (LD) in x-ray absorption, diffraction, transport, and magnetization measurements on thin La(0.7)Sr(0.3)MnO(3) films grown on different substrates, allow identification of a peculiar interface effect, related just to the presence of the interface. We report the LD signature of preferential 3d-e(g)(3z(2)-r(2)) occupation at the interface, suppressing the double exchange mechanism. This surface orbital reconstruction is opposite to that favored by residual strain and is independent of dipolar fields, the chemical nature of the substrate and the presence of capping layers.
  Physical Review Letters 04/2008; 100(13):137401. · 7.37 Impact Factor
• Article: Evidence of orbital reconstruction at interfaces in ultrathin La(0.67)Sr(0.33)MnO(3) films

  A. Tebano, C. Aruta, S. Sanna, P. G. Medaglia, G. Balestrino, A. A. Sidorenko, R. De Renzi, G. Ghiringhelli, L. Braicovich, V. Bisogni, N. B. Brookes
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  ABSTRACT: ISI Document Delivery No.: 283XR
  Phys. Rev. Lett. 01/2008; 100:4.
• Source

  Available from: Roberto De Renzi

  Article: Evidence of orbital reconstruction at interfaces in La0.67Sr0.33MnO3 films

  A. Tebano, C. Aruta, S. Sanna, P. G. Medaglia, G. Balestrino, A. A. Sidorenko, R De Renzi, G. Ghiringhelli, L. Braicovich, V. Bisogni, N. B. Brookes
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  ABSTRACT: Electronic properties of transition metal oxides at interfaces are influenced by strain, electric polarization and oxygen diffusion. Linear dichroism (LD) x-ray absorption, diffraction, transport and magnetization on thin La0.7Sr0.3MnO3 films, allow identification of a peculiar universal interface effect. We report the LD signature of preferential 3d-eg(3z2-r2) occupation at the interface, suppressing the double exchange mechanism. This surface orbital reconstruction is opposite of that favored by residual strain and independent of dipolar fields, chemical nature of the substrate and capping. Comment: 13 pages, 5 figures
  08/2007;
• Article: Evidence of orbital reconstruction at interfaces in ultrathin La(0.67)Sr(0.33)MnO(3) films

  A. Tebano, C. Aruta, S. Sanna, P. G. Medaglia, G. Balestrino, A. A. Sidorenko, R. De Renzi, G. Ghiringhelli, L. Braicovich, V. Bisogni, N. B. Brookes
  Physical Review Letters 01/1970; 100(13). · 7.37 Impact Factor
• Source

  Available from: M. Salluzzo

  Article: Weak magnetism in insulating and superconducting cuprates

  G. M. De Luca, G. Ghiringhelli, M. Moretti Sala, S. Di Matteo, M. W. Haverkort, H. Berger, V. Bisogni, J. C. Cezar, N. B. Brookes, M. Salluzzo
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  ABSTRACT: X-ray magnetic circular dichroism provides evidence of an out-of-plane spin moment in undoped and doped cuprates. In La2CuO4 this moment is related to the canting of the antiferromagnetically ordered Cu2+ spins caused by the Dzyaloshinskii-Moriya interaction within the CuO2 planes. This canting gives rise to the well-known weak ferromagnetism in high magnetic fields. We find a similar behavior in doped compounds, both in the normal and in the superconducting state, but with a different temperature dependence typical of paramagnetic systems. This result suggests that, together with short-range in-plane antiferromagnetic correlations, the Dzyaloshinskii-Moriya interaction survives up to optimal doping and in the superconducting state.
  Phys. Rev. B. 82(21).
• Article: Neutral 3d excitations in insulating VO_ {2} as seen with resonant inelastic x-ray scattering at the VL_ {3, 2} edges

  L. Braicovich, G. Ghiringhelli, L. H. Tjeng, V. Bisogni, C. Dallera, A. Piazzalunga, W. Reichelt, N. B. Brookes
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  ABSTRACT: We present resonant inelastic x-ray scattering (RIXS) results on insulating monoclinic VO2 with excitation across the L2,3 edges of vanadium. The spectra measured near threshold in the L3 region and in the L2 region show a Raman behavior with a clear peak around 0.9 eV transferred energy. The analysis of the data allows the neutral excitation spectrum of the system up to about 2–2.5 eV to be determined. These excitations are due to dd transitions, whose main contributions are discussed. The possibility of {d1;d1→d2;d0} charge fluctuations within a dimer in RIXS is also discussed. The results are compared with available information on optical constants and on electron energy loss spectroscopy. Due to the low symmetry of the system, there is a similarity between the Raman spectrum obtained with RIXS and the optical absorption spectrum.
  Phys. Rev. B. 76(12).
• Article: Momentum and polarization dependence of single-magnon spectral weight for Cu L-3-edge resonant inelastic x-ray scattering from layered cuprates

  L Braicovich, M M Sala, L J P Ament, V Bisogni, M Minola, G Balestrino, D Di Castro, G M De Luca, M Salluzzo, G Ghiringhelli, J Brink
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  ABSTRACT: Recently it was predicted theoretically and confirmed experimentally that in cuprates single-magnon dispersions can be mapped out with resonant inelastic x-ray scattering (RIXS) at the copper L-3 edge. To further establish RIXS as a viable technique we investigate the momentum and incident photon polarization dependence of the single-magnon spectral weight in a variety of layered undoped antiferromagnetic compounds. The agreement of experimental and theoretical results bolsters the assignment of RIXS spectral features to single magnons. This detailed analysis allows to disentangle single-magnon scattering from other spectral contributions. Moreover, it is a necessary premise for future research aimed at investigating processes that modulate spectral weights beyond the predictions of linear spin-wave theory.
  Physical Review B. 81(17).
• Article: Orbital Reconstruction and the Two-Dimensional Electron Gas at the LaAlO(3)/SrTiO(3) Interface

  M Salluzzo, J C Cezar, N B Brookes, V Bisogni, G M De Luca, C Richter, S Thiel, J Mannhart, M Huijben, A Brinkman, G Rijnders, G Ghiringhelli
  [show abstract] [hide abstract]
  ABSTRACT: In 2004, Ohtomo and Hwang discovered that an electron gas is created at the interface between insulating LaAlO(3) and SrTiO(3) compounds. Here we show that the generation of a conducting electron gas is related to an orbital reconstruction occurring at the LaAlO(3)/SrTiO(3) interface. Our results are based on extensive investigations of the electronic properties and of the orbital structure of the interface using x-ray absorption spectroscopy. In particular, we find that the degeneracy of the Ti 3d states is fully removed and that the Ti 3d(xy) levels become the first available states for conducting electrons.
  PHYSICAL REVIEW LETTERS. 102(16).
• Article: Energy and symmetry of dd excitations in undoped layered cuprates measured by Cu L(3) resonant inelastic x-ray scattering

  M Moretti Sala, V Bisogni, C Aruta, G Balestrino, H Berger, N B Brookes, G M Luca, D Di Castro, M Grioni, M Guarise, P G Medaglia, Miletto F Granozio, M Minola, P Perna, M Radovic, M Salluzzo, T Schmitt, K J Zhou, L Braicovich, G Ghiringhelli
  New Journal of Physics. 13.
• Article: Energy and symmetry of dd excitations in undoped layered cuprates measured by Cu L(3) resonant inelastic x-ray scattering

  M. Moretti Sala, V. Bisogni, C. Aruta, G. Balestrino, H. Berger, N. B. Brookes, G. M. de Luca, D. Di Castro, M. Grioni, M. Guarise, P. G. Medaglia, F. Miletto Granozio, M. Minola, P. Perna, M. Radovic, M. Salluzzo, T. Schmitt, K. J. Zhou, L. Braicovich, G. Ghiringhelli
  13.
• Source

  Available from: Jeroen van den Brink

  Article: Momentum and polarization dependence of single-magnon spectral weight for Cu L-3-edge resonant inelastic x-ray scattering from layered cuprates

  L. Braicovich, M. M. Sala, L. J. P. Ament, V. Bisogni, M. Minola, G. Balestrino, D. Di Castro, G. M. De Luca, M. Salluzzo, G. Ghiringhelli, J. van den Brink
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  ABSTRACT: Times Cited: 0
  81.
• Source

  Available from: Jeroen van den Brink

  Article: Magnetic Excitations and Phase Separation in the Underdoped La2-xSrxCuO4 Superconductor Measured by Resonant Inelastic X-Ray Scattering

  L. Braicovich, J. van den Brink, V. Bisogni, M. M. Sala, L. J. P. Ament, N. B. Brookes, G. M. De Luca, M. Salluzzo, T. Schmitt, V. N. Strocov, G. Ghiringhelli
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  ABSTRACT: Times Cited: 9
  104.