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1. Surfaces of colloidal PbSe nanocrystals probed by thin-film positron annihilation spectroscopy

Author

Chai, L. (author), Al-Sawai, W. (author), Gao, Y. (author), Houtepen, A.J. (author), Mijnarends, P.E. (author), Barbiellini, B. (author), Schut, H. (author), Van Schaarenburg, L.C. (author), Van Huis, M.A. (author), Ravelli, L. (author), Egger, W. (author), Kaprzyk, S. (author), Bansil, A. (author), Eijt, S.W.H. (author), Chai, L. (author), Al-Sawai, W. (author), Gao, Y. (author), Houtepen, A.J. (author), Mijnarends, P.E. (author), Barbiellini, B. (author), Schut, H. (author), Van Schaarenburg, L.C. (author), Van Huis, M.A. (author), Ravelli, L. (author), Egger, W. (author), Kaprzyk, S. (author), Bansil, A. (author), and Eijt, S.W.H. (author)

Abstract

Positron annihilation lifetime spectroscopy and positron-electron momentum density (PEMD) studies on multilayers of PbSe nanocrystals (NCs), supported by transmission electron microscopy, show that positrons are strongly trapped at NC surfaces, where they provide insight into the surface composition and electronic structure of PbSe NCs. Our analysis indicates abundant annihilation of positrons with Se electrons at the NC surfaces and with O electrons of the oleic ligands bound to Pb ad-atoms at the NC surfaces, which demonstrates that positrons can be used as a sensitive probe to investigate the surface physics and chemistry of nanocrystals inside multilayers. Ab initio electronic structure calculations provide detailed insight in the valence and semi-core electron contributions to the positron-electron momentum density of PbSe. Both lifetime and PEMD are found to correlate with changes in the particle morphology characteristic of partial ligand removal., RST/Radiation, Science and Technology, Applied Sciences

Published
2013
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2. Surfaces of colloidal PbSe nanocrystals probed by thin-film positron annihilation spectroscopy

Author

Chai, L. (author), Al-Sawai, W. (author), Gao, Y. (author), Houtepen, A.J. (author), Mijnarends, P.E. (author), Barbiellini, B. (author), Schut, H. (author), Van Schaarenburg, L.C. (author), Van Huis, M.A. (author), Ravelli, L. (author), Egger, W. (author), Kaprzyk, S. (author), Bansil, A. (author), Eijt, S.W.H. (author), Chai, L. (author), Al-Sawai, W. (author), Gao, Y. (author), Houtepen, A.J. (author), Mijnarends, P.E. (author), Barbiellini, B. (author), Schut, H. (author), Van Schaarenburg, L.C. (author), Van Huis, M.A. (author), Ravelli, L. (author), Egger, W. (author), Kaprzyk, S. (author), Bansil, A. (author), and Eijt, S.W.H. (author)

Abstract

Positron annihilation lifetime spectroscopy and positron-electron momentum density (PEMD) studies on multilayers of PbSe nanocrystals (NCs), supported by transmission electron microscopy, show that positrons are strongly trapped at NC surfaces, where they provide insight into the surface composition and electronic structure of PbSe NCs. Our analysis indicates abundant annihilation of positrons with Se electrons at the NC surfaces and with O electrons of the oleic ligands bound to Pb ad-atoms at the NC surfaces, which demonstrates that positrons can be used as a sensitive probe to investigate the surface physics and chemistry of nanocrystals inside multilayers. Ab initio electronic structure calculations provide detailed insight in the valence and semi-core electron contributions to the positron-electron momentum density of PbSe. Both lifetime and PEMD are found to correlate with changes in the particle morphology characteristic of partial ligand removal., RST/Radiation, Science and Technology, Applied Sciences

Published
2013
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3. Bulk Fermi surface and momentum density in heavily doped La2?xSrxCuO4 using high-resolution Compton scattering and positron annihilation spectroscopies

Author

Al-Sawai, W. (author), Barbiellini, B. (author), Sakurai, Y. (author), Itou, M. (author), Mijnarends, P.E. (author), Markiewicz, R.S. (author), Kaprzyk, S. (author), Wakimoto, S. (author), Fujita, M. (author), Basak, S. (author), Lin, H. (author), Wang, Y.J. (author), Eijt, S.W.H. (author), Schut, H. (author), Yamada, K. (author), Bansil, A. (author), Al-Sawai, W. (author), Barbiellini, B. (author), Sakurai, Y. (author), Itou, M. (author), Mijnarends, P.E. (author), Markiewicz, R.S. (author), Kaprzyk, S. (author), Wakimoto, S. (author), Fujita, M. (author), Basak, S. (author), Lin, H. (author), Wang, Y.J. (author), Eijt, S.W.H. (author), Schut, H. (author), Yamada, K. (author), and Bansil, A. (author)

Abstract

We have observed the bulk Fermi surface (FS) in an overdoped (x=0.3) single crystal of La2?xSrxCuO4 by using Compton scattering. A two-dimensional (2D) momentum density reconstruction from measured Compton profiles yields a clear FS signature in the third Brillouin zone along [100]. The quantitative agreement between density functional theory (DFT) calculations and momentum density experiment suggests that Fermi-liquid physics is restored in the overdoped regime. In particular the predicted FS topology is found to be in good accord with the corresponding experimental data. We find similar quantitative agreement between the measured 2D angular correlation of positron annihilation radiation (2D-ACAR) spectra and the DFT-based computations. However, 2D-ACAR does not give such a clear signature of the FS in the extended momentum space in either the theory or the experiment., RRR/Radiation, Radionuclides and Reactors, Applied Sciences

Published
2012
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4. Lindhard and RPA susceptibility computations in extended momentum space in electron-doped cuprates

Author

Wang, Y.J. (author), Barbiellini, B. (author), Lin, H. (author), Das, T. (author), Basak, S. (author), Mijnarends, P.E. (author), Kaprzyk, S. (author), Markiewicz, R.S. (author), Bansil, A. (author), Wang, Y.J. (author), Barbiellini, B. (author), Lin, H. (author), Das, T. (author), Basak, S. (author), Mijnarends, P.E. (author), Kaprzyk, S. (author), Markiewicz, R.S. (author), and Bansil, A. (author)

Abstract

We present an approximation for efficient calculation of the Lindhard susceptibility ?L(q,?) in a periodic system through the use of simple products of real space functions and the fast Fourier transform (FFT). The method is illustrated by providing ?L(q,?) results for the electron doped cuprate Nd2?xCexCuO4 extended over several Brillouin zones. These results are relevant for interpreting inelastic x-ray scattering spectra from cuprates., RRR/Radiation, Radionuclides and Reactors, Applied Sciences

Published
2012
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5. Bulk Fermi surface and momentum density in heavily doped La2?xSrxCuO4 using high-resolution Compton scattering and positron annihilation spectroscopies

Author

Al-Sawai, W. (author), Barbiellini, B. (author), Sakurai, Y. (author), Itou, M. (author), Mijnarends, P.E. (author), Markiewicz, R.S. (author), Kaprzyk, S. (author), Wakimoto, S. (author), Fujita, M. (author), Basak, S. (author), Lin, H. (author), Wang, Y.J. (author), Eijt, S.W.H. (author), Schut, H. (author), Yamada, K. (author), Bansil, A. (author), Al-Sawai, W. (author), Barbiellini, B. (author), Sakurai, Y. (author), Itou, M. (author), Mijnarends, P.E. (author), Markiewicz, R.S. (author), Kaprzyk, S. (author), Wakimoto, S. (author), Fujita, M. (author), Basak, S. (author), Lin, H. (author), Wang, Y.J. (author), Eijt, S.W.H. (author), Schut, H. (author), Yamada, K. (author), and Bansil, A. (author)

Abstract

We have observed the bulk Fermi surface (FS) in an overdoped (x=0.3) single crystal of La2?xSrxCuO4 by using Compton scattering. A two-dimensional (2D) momentum density reconstruction from measured Compton profiles yields a clear FS signature in the third Brillouin zone along [100]. The quantitative agreement between density functional theory (DFT) calculations and momentum density experiment suggests that Fermi-liquid physics is restored in the overdoped regime. In particular the predicted FS topology is found to be in good accord with the corresponding experimental data. We find similar quantitative agreement between the measured 2D angular correlation of positron annihilation radiation (2D-ACAR) spectra and the DFT-based computations. However, 2D-ACAR does not give such a clear signature of the FS in the extended momentum space in either the theory or the experiment., RRR/Radiation, Radionuclides and Reactors, Applied Sciences

Published
2012
Full Text
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6. Lindhard and RPA susceptibility computations in extended momentum space in electron-doped cuprates

Author

Wang, Y.J. (author), Barbiellini, B. (author), Lin, H. (author), Das, T. (author), Basak, S. (author), Mijnarends, P.E. (author), Kaprzyk, S. (author), Markiewicz, R.S. (author), Bansil, A. (author), Wang, Y.J. (author), Barbiellini, B. (author), Lin, H. (author), Das, T. (author), Basak, S. (author), Mijnarends, P.E. (author), Kaprzyk, S. (author), Markiewicz, R.S. (author), and Bansil, A. (author)

Abstract

We present an approximation for efficient calculation of the Lindhard susceptibility ?L(q,?) in a periodic system through the use of simple products of real space functions and the fast Fourier transform (FFT). The method is illustrated by providing ?L(q,?) results for the electron doped cuprate Nd2?xCexCuO4 extended over several Brillouin zones. These results are relevant for interpreting inelastic x-ray scattering spectra from cuprates., RRR/Radiation, Radionuclides and Reactors, Applied Sciences

Published
2012
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7. Proposal to determine the Fermi-surface topology of a doped iron-based superconductor using bulk-sensitive Fourier-transform Compton scattering

Author

Wang, Y.J. (author), Lin, H. (author), Barbiellini, B. (author), Mijnarends, P.E. (author), Kaprzyk, S. (author), Markiewicz, R.S. (author), Bansil, A. (author), Wang, Y.J. (author), Lin, H. (author), Barbiellini, B. (author), Mijnarends, P.E. (author), Kaprzyk, S. (author), Markiewicz, R.S. (author), and Bansil, A. (author)

Abstract

We have carried out first-principles calculations of the Compton scattering spectra to demonstrate that the filling of the hole Fermi surface in LaO1?xFxFeAs produces a distinct signature in the Fourier-transformed Compton spectrum when the momentum transfer vector lies along the [100] direction. We thus show how the critical concentration xc, where hole Fermi-surface pieces are filled up and the superconductivity mediated by antiferromagnetic spin fluctuations is expected to be suppressed, can be obtained in a bulk-sensitive manner., Radiation, Radionuclides and Reactors, Applied Sciences

Published
2010
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8. Proposal to determine the Fermi-surface topology of a doped iron-based superconductor using bulk-sensitive Fourier-transform Compton scattering

Author

Wang, Y.J. (author), Lin, H. (author), Barbiellini, B. (author), Mijnarends, P.E. (author), Kaprzyk, S. (author), Markiewicz, R.S. (author), Bansil, A. (author), Wang, Y.J. (author), Lin, H. (author), Barbiellini, B. (author), Mijnarends, P.E. (author), Kaprzyk, S. (author), Markiewicz, R.S. (author), and Bansil, A. (author)

Abstract

We have carried out first-principles calculations of the Compton scattering spectra to demonstrate that the filling of the hole Fermi surface in LaO1?xFxFeAs produces a distinct signature in the Fourier-transformed Compton spectrum when the momentum transfer vector lies along the [100] direction. We thus show how the critical concentration xc, where hole Fermi-surface pieces are filled up and the superconductivity mediated by antiferromagnetic spin fluctuations is expected to be suppressed, can be obtained in a bulk-sensitive manner., Radiation, Radionuclides and Reactors, Applied Sciences

Published
2010
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13. Two-dimensional folding technique for enhancing Fermi surface signatures in the momentum density: Application to Compton scattering data from an Al-3 at. % Li disordered alloy

Author

Matsumoto, I. (author), Kwiatkowska, J. (author), Maniawski, F. (author), Itou, M. (author), Kawata, H. (author), Shiotani, N. (author), Kaprzyk, S. (author), Mijnarends, P.E. (author), Barbiellini, B. (author), Bansil, A. (author), Matsumoto, I. (author), Kwiatkowska, J. (author), Maniawski, F. (author), Itou, M. (author), Kawata, H. (author), Shiotani, N. (author), Kaprzyk, S. (author), Mijnarends, P.E. (author), Barbiellini, B. (author), and Bansil, A. (author)

Published
2001

15. Two-dimensional folding technique for enhancing Fermi surface signatures in the momentum density: Application to Compton scattering data from an Al-3 at. % Li disordered alloy

Author

Matsumoto, I. (author), Kwiatkowska, J. (author), Maniawski, F. (author), Itou, M. (author), Kawata, H. (author), Shiotani, N. (author), Kaprzyk, S. (author), Mijnarends, P.E. (author), Barbiellini, B. (author), Bansil, A. (author), Matsumoto, I. (author), Kwiatkowska, J. (author), Maniawski, F. (author), Itou, M. (author), Kawata, H. (author), Shiotani, N. (author), Kaprzyk, S. (author), Mijnarends, P.E. (author), Barbiellini, B. (author), and Bansil, A. (author)

Published
2001

17. High-resolution Compton scattering study of the electron momentum density in Al

Author

Ohata, T. (author), Itou, M. (author), Matsumoto, I. (author), Sakurai, Y. (author), Kawata, H. (author), Shiotani, N. (author), Kaprzyk, S. (author), Mijnarends, P.E. (author), Bansil, A. (author), Ohata, T. (author), Itou, M. (author), Matsumoto, I. (author), Sakurai, Y. (author), Kawata, H. (author), Shiotani, N. (author), Kaprzyk, S. (author), Mijnarends, P.E. (author), and Bansil, A. (author)

Published
2000

18. High-resolution Compton scattering study of the electron momentum density in Al

Author

Ohata, T. (author), Itou, M. (author), Matsumoto, I. (author), Sakurai, Y. (author), Kawata, H. (author), Shiotani, N. (author), Kaprzyk, S. (author), Mijnarends, P.E. (author), Bansil, A. (author), Ohata, T. (author), Itou, M. (author), Matsumoto, I. (author), Sakurai, Y. (author), Kawata, H. (author), Shiotani, N. (author), Kaprzyk, S. (author), Mijnarends, P.E. (author), and Bansil, A. (author)

Published
2000

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