Spin flip inelastic scattering in electron energy loss spectroscopy of a ferromagnetic metal

Bocchetta, C.J.; Tosatti, Erio; Yin, Siqi

doi:10.1007/bf01307311

Cited by 12 publications

(4 citation statements)

References 12 publications

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“…Theoretically, the triplet exciton is the Sϭ1 ground state in a nonmagnetic insulator, and can thus in full legitimacy be introduced in a ground-state calculation by forcing a total spin of one. 11 Experimentally, triplet excitons could, for example, be generated by energy loss exchange processes by impact of lowenergy electrons, 12 whereby an incoming spin down electron drops in energy to occupy an empty conduction state, while kicking upward in energy a spin up valence electron, which creates the hole. Although with an energy and lifetime that are presently unknown, a long-lived triplet Sϭ1 exciton must exist in PE, as it does in all other molecular solids, with an excitation energy somewhat below the ordinary, singlet exciton, and thus below the band gap of 8.8 eV.…”

Section: Computational Techniquesmentioning

confidence: 99%

Trapping of excitons at chemical defects in polyethylene

Ceresoli

Tosatti

Scandolo

et al. 2004

The Journal of Chemical Physics

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In a previous paper we studied an injected electron-hole pair in crystalline polyethylene (PE) and found that the exciton becomes weakly self-trapped in a narrow interchain pocket comprised between two gauche defects. Despite the large energy stored in the trapped excitation, there did not appear to be a direct nonradiative channel for electron-hole recombination. Actual polyethylene systems of practical use are, however, neither crystalline nor pure. To understand the fate of an electron-hole pair in the impure case, we studied by ab initio simulations the evolution of an exciton trapped on three common chemical defects found in polyethylene: a grafted carbonyl (C=O); an intrachain vinyl group (C=C); a grafted carboxyl (COOH). Ab initio simulations lead to predict three different outcomes: trapping, nonradiative recombination, and homolitic bond-breaking, respectively. This suggests that extrinsic self-trapping of electron-hole pairs over chemical defects inside the quasicrystalline fraction of PE could be relevant for electrical damage in high-voltage cables.

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Section: Computational Techniquesmentioning

confidence: 99%

Trapping of excitons at chemical defects in polyethylene

Ceresoli

Tosatti

Scandolo

et al. 2004

The Journal of Chemical Physics

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“…Theoretically, a triplet exciton is the S = 1 ground state, and can in principle be introduced in a calculation by forcing a total spin of one in a spin-polarized calculation [17]. Experimentally, triplet excitons could be created by impact energy loss exchange processes of low energy electrons, [18] whereby an incoming spin down electron will fall in energy to occupy an empty conduction state, while kicking away a spin up electron, and thus creating a spin up valence hole. Although its actual energy location and lifetime are presently unknown, a long-lived triplet S = 1 exciton must surely exist in PE, as in all other molecular solids, with an excitation energy below the ordinary, singlet excitation gap.…”

Section: Computational Techniquesmentioning

confidence: 99%

Exciton self-trapping in bulk polyethylene

Ceresoli

Righi

Tosatti

et al. 2005

J. Phys.: Condens. Matter

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Abstract. We studied theoretically the behavior of an injected electron-hole pair in crystalline polyethylene. Time-dependent adiabatic evolution by ab-initio molecular dynamics simulations show that the pair will become self-trapped in the perfect crystal, with a trapping energy of about 0.38 eV, with formation of a pair of trans-gauche conformational defects, three C 2 H 4 units apart on the same chain. The electron is confined in the inter-chain pocket created by a local, 120 • rotation of the chain between the two defects, while the hole resides on the chain and is much less bound. Despite the large energy stored in the trapped excitation, there does not appear to be a direct non-radiative channel for electron-hole recombination. This suggests that intrinsic selftrapping of electron-hole pairs inside the ideal quasi-crystalline fraction of PE might not be directly relevant for electrical damage in high-voltage cables.

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“…Spin-polarized electron energy loss spectroscopy (SPEELS) is a powerful tool to study electron excitation dynamics in ferromagnetic and paramagnetic solids. This potential was pointed out in theory, [1][2][3] and experiment 4,5 in the middle 1980s already. In brief, the experiment requires a spin-polarized electron source, 6 an energy analyzer for the scattered electron, and a spin polarization analyzer.…”

Section: Introductionmentioning

confidence: 73%

Design and performance of a spin-polarized electron energy loss spectrometer with high momentum resolution

Vasilyev

Kirschner

2016

Review of Scientific Instruments

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We describe a new "complete" spin-polarized electron energy loss spectrometer comprising a spin-polarized primary electron source, an imaging electron analyzer, and a spin analyzer of the "spin-polarizing mirror" type. Unlike previous instruments, we have a high momentum resolution of less than 0.04 Å(-1), at an energy resolution of 90-130 meV. Unlike all previous studies which reported rather broad featureless data in both energy and angle dependence, we find richly structured spectra depending sensitively on small changes of the primary energy, the kinetic energy after scattering, and of the angle of incidence. The key factor is the momentum resolution.

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Spin flip inelastic scattering in electron energy loss spectroscopy of a ferromagnetic metal

Cited by 12 publications

References 12 publications

Trapping of excitons at chemical defects in polyethylene

Trapping of excitons at chemical defects in polyethylene

Exciton self-trapping in bulk polyethylene

Design and performance of a spin-polarized electron energy loss spectrometer with high momentum resolution

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