High-Resolution High-Energy Photoemission Study of Rare-Earth Heavy Fermion Systems

Sekiyama, A.; Imada, S.; Yamasaki, Akira; Suga, S.

doi:10.1007/3-540-68133-7_13

Cited by 6 publications

(4 citation statements)

References 68 publications

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“…However, a detailed understanding of the dispersion behavior of electronic states, for example, in transition metal compounds such as cuprate or pnictide high-T c superconductors, 1,2 4f rare-earth systems, 3 or 3d transition metals 4 is still missing. In the case of ferromagnetic transition metals, an extensive experimental work in this respect has been carried out over the last 30 years.…”

Section: Introductionmentioning

confidence: 99%

Effects of spin-dependent quasiparticle renormalization in Fe, Co, and Ni photoemission spectra:An experimental and theoretical study

Sánchez-Barriga

Braun²,

Minář³

et al. 2012

Phys. Rev. B

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We have investigated the spin-dependent quasiparticle lifetimes and the strength of electron correlation effects in the ferromagnetic 3d transition metals Fe, Co, and Ni by means of spin-and angle-resolved photoemission spectroscopy. The experimental data are accompanied by state-of-the-art many-body calculations within the dynamical mean-field theory and the three-body scattering approximation, including fully relativistic calculations of the photoemission process within the one-step model. Our quantitative analysis reveals that inclusion of local many-body Coulomb interactions are of ultimate importance for a realistic description of correlation effects in ferromagnetic 3d transition metals. However, we found that more sophisticated many-body calculations with larger modifications in the case of Fe and Co are still needed to improve the quantitative agreement between experiment and theory. In general, it turned out that not only the dispersion behavior of energetic structures should be affected by nonlocal correlations but also the line widths of most of the photoemission peaks are underestimated by the current theoretical approaches. The increasing values of the on-site Coulomb interaction parameter U and the band narrowing of majority spin states obtained when moving from Fe to Ni indicate that the effect of nonlocal correlations becomes weaker with increasing atomic number, whereas correlation effects tend to be stronger.

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Section: Introductionmentioning

confidence: 99%

Effects of spin-dependent quasiparticle renormalization in Fe, Co, and Ni photoemission spectra:An experimental and theoretical study

Sánchez-Barriga

Braun²,

Minář³

et al. 2012

Phys. Rev. B

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“…Over the last decades, the electronic structure and the dynamics of electronic states in solids have attracted a lot of attention. A better understanding of the binding energies and quasiparticle lifetimes in correlated systems like 3d ferromagnets 1 , transition metal oxides 2 , 4f rareearths 3 or high-T c superconductors 4 has been achieved, together with important experimental progress in photoelectron and related spectroscopies. 5 On the theoretical side, the application of density functional theory (DFT) in the local density approximation 6 (LDA) has contributed with numerous calculations of single-particle E(k) band dispersions of solids, surfaces, and ultrathin films.…”

Section: Introductionmentioning

confidence: 99%

Quantitative determination of spin-dependent quasiparticle lifetimes and electronic correlations in hcp cobalt

Sánchez-Barriga

Minář²,

Braun³

et al. 2010

Phys. Rev. B

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We report on a quantitative investigation of the spin-dependent quasiparticle lifetimes and electron correlation effects in ferromagnetic hcp Co͑0001͒ by means of spin-and angle-resolved photoemission spectroscopies. The experimental spectra are compared in detail to state-of-the-art many-body calculations within the dynamical mean-field theory and the three-body scattering approximation, including a full calculation of the one-step photoemission process. From this comparison we conclude that although strong local many-body Coulomb interactions are of major importance for the qualitative description of correlation effects in Co, more sophisticated many-body calculations are needed in order to improve the quantitative agreement between theory and experiment, in particular, concerning the linewidths. The quality of the overall agreement obtained for Co indicates that the effect of nonlocal correlations becomes weaker with increasing atomic number.

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“…Namely, whether a large Fermi-surface distortion is a weak perturbation on the lifetime broadening of TSSs or there are preferential momentum-space directions where this distortion results into a substantial modification of the scattering rates of the surface-state electrons. ARPES represents an ideal technique for such a purpose, as it is a well-established method to determine the lifetime broadening of electronic states, 36,37 not only in strongly correlated systems such as transition-metal oxides, 38 4f rare-earths, 39 high-T c superconductors 40,41 or 3d ferromagnets, [42][43][44] but also in TIs. [45][46][47] Moreover, ARPES has recently become the most powerful tool in systematically revealing the linear dispersion of TSSs in energy and momentum space.…”

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confidence: 99%

Anisotropic effect of warping on the lifetime broadening of topological surface states in angle-resolved photoemission fromBi2Te3

et al. 2014

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We analyze the strong hexagonal warping of the Dirac cone of Bi2Te3 by angle-resolved photoemission. Along ΓM, the dispersion deviates from a linear behavior meaning that the Dirac cone is warped outwards and not inwards. We show that this introduces an anisotropy in the lifetime broadening of the topological surface state which is larger along ΓK. The result is not consistent with nesting. Based on the theoretically predicted behavior of the ground-state spin texture of a strongly warped Dirac cone, we propose spin-dependent scattering processes as explanation for the anisotropic scattering rates. These results could help paving the way for optimizing future spintronic devices using topological insulators and controlling surface-scattering processes via external gate voltages.Topological insulators (TIs) are characterized by an insulating bulk energy gap and gapless spin-polarized Dirac-cone surface states with electron spins locked perpendicular to their linear momenta. 1,2 This peculiar spin texture is believed to play a central role in inducing exotic quantum phenomena 2,3 , novel magnetic-spin physics, 4,5 as well as in the development of future spin-based lowpower transistors among a variety of applications. Such perpendicular locking can be realized if spins of electrons occupying the Dirac cone move around in ideally circular constant-energy contours between the Dirac point and the Fermi level. 6 Owing to the spin-momentum locking, electrons on the surfaces of TIs are protected from backscattering, 7 an effect that might be of crucial importance in the generation of spin currents with reduced dissipation, 8 coherent spin rotation, 9 spin-orbit qubits, 10 as well as in other applications such as manipulation of photon-polarization driven spin currents in real devices. 11 The spin texture of the Dirac cone can be affected by the presence of hexagonal warping, 12 i.e., the Dirac cone is deformed in such a way that from the Dirac point to the energy of the Fermi level the constantenergy contours develop from an ideally circular shape to a hexagon, and subsequently to a snowflake-like Fermi surface. This strong distortion of the Dirac cone might open up new possibilities for observing other interesting phenomena, such as the breaking of time-reversal symmetry and the surface quantum Hall effect under applied magnetic fields parallel to the surface, 12 enhanced surface scattering or the formation of surface spin-density waves. 12,13 In the context of exploring these possibilities, the observation and importance of hexagonal warping in the band dispersions of the topological surface states (TSSs), 14-16 as well as its theoretical description, 12,17,18 has stimulated a manifold of theoretical and experimental investigations on TIs. The strong influence of warping on the spin texture of TSSs giving rise to a finite outof-plane spin orientation was theoretically predicted, 12 and by means of spin-resolved angle-resolved photoemission (SR-ARPES) experimentally observed. 19 That in the presence of warping the electro...

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High-Resolution High-Energy Photoemission Study of Rare-Earth Heavy Fermion Systems

Cited by 6 publications

References 68 publications

Effects of spin-dependent quasiparticle renormalization in Fe, Co, and Ni photoemission spectra:An experimental and theoretical study

Effects of spin-dependent quasiparticle renormalization in Fe, Co, and Ni photoemission spectra:An experimental and theoretical study

Quantitative determination of spin-dependent quasiparticle lifetimes and electronic correlations in hcp cobalt

Anisotropic effect of warping on the lifetime broadening of topological surface states in angle-resolved photoemission fromBi2Te3

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