Production of high circular polarization by ion surface scattering of ferromagnets

Kupfer, E.; Gabriel, H.; Schröder, Heinz C.

doi:10.1007/bf01409509

Cited by 20 publications

(7 citation statements)

References 7 publications

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“…Thus, via fine-structure interaction the anisotropy of total angular momenta of atomic terms is modified relative to that resulting from the capture of unpolarized electrons. 5 ' 6 This Letter gives first clear experimental evidence that the interaction of fast ions with a magnetic surface results in a modification of the orientation of excited terms observed after grazing ion-surface scattering. We show that this modification is directly related to the spin polarization of captured electrons.…”

Section: S// = [/(Cj-)-/(ct + ) ] / [ / ( C T -) + / ( C T + ) ] mentioning

confidence: 94%

“…5,11,12 In our experiments we scattered He + , N + , and Ar + ions with energies between 10 and 250 keV at grazing angles O < 1° off a clean, magnetized Fe(l 10) surface at 296…”

Section: S// = [/(Cj-)-/(ct + ) ] / [ / ( C T -) + / ( C T + ) ] mentioning

confidence: 99%

“…5,11,12 In our experiments we scattered He + , N + , and Ar + ions with energies between 10 and 250 keV at grazing angles O < 1° off a clean, magnetized Fe(l 10) surface at room temperature. Normal to the plane of scattering, we observed the polarized fluorescence light by an achromatic quarter-wave plate, a Glan Thompson polarizer, a McPherson Mod.218 spectrometer, and a cooled RCA 31034A photomultiplier (Fig.…”

Section: S// = [/(Cj-)-/(ct + ) ] / [ / ( C T -) + / ( C T + ) ] mentioning

confidence: 99%

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Polarized Light Emission after Grazing Ion-Surface Scattering Due to Capture of Spin-Polarized Electrons

et al. 1989

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We have observed the capture of polarized electrons into excited terms of atoms after the interaction of fast ions with a magnetized Fe(llO) surface at grazing incidence. The spin polarization of captured electrons results in a modified circular polarization fraction of fluorescence light. This experiment has considerable potential as a new analytical tool for investigating surface magnetism with extreme surface sensitivity, as a method for detailed studies of ion-surface interaction, and as a means to produce nuclear spin-polarized beams.PACS numbers: 79.20.Nc, 34.50.Fa, 75.50.Bb We report on first investigations of polarized light emission after scattering of fast ions from a magnetized surface at grazing incidence. The new technique allows us to detect the electron spin polarization at magnetized surfaces via electron capture into excited terms of scattered atoms. This is an important development in the studying of surface magnetism by ion scattering which was pioneered by Rau and Sizmann, l who scattered fast deuterons from magnetized targets and observed the capture of polarized electrons in the Is ground term of deuterium via an asymmetry in the nuclear T(d,n) 4 He reaction. Despite the fact that the mechanisms of the capture process are only vaguely understood, this technique has been used to study long-and short-range magnetic order at surfaces. 2 The basic idea of the experiments reported here is that an ensemble of excited atomic terms with anisotropically distributed total angular momenta generally decays via the emission of polarized light. Atomic anisotropy (orientation) can be induced via excitation of atoms by grazing ion-surface scattering and/or by capture of polarized electrons. The orientation of atomic angular momenta can be probed simply by the fraction of circular polarization in the fluorescence light as given by the Stokes parameter 3 4S// = [/(cJ-)-/(cT + ) ] / [ / ( c T -) + / ( c T + ) ] ,where I{a~) and /(

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Section: S// = [/(Cj-)-/(ct + ) ] / [ / ( C T -) + / ( C T + ) ] mentioning

confidence: 94%

“…5,11,12 In our experiments we scattered He + , N + , and Ar + ions with energies between 10 and 250 keV at grazing angles O < 1° off a clean, magnetized Fe(l 10) surface at 296…”

Section: S// = [/(Cj-)-/(ct + ) ] / [ / ( C T -) + / ( C T + ) ] mentioning

confidence: 99%

Section: S// = [/(Cj-)-/(ct + ) ] / [ / ( C T -) + / ( C T + ) ] mentioning

confidence: 99%

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Polarized Light Emission after Grazing Ion-Surface Scattering Due to Capture of Spin-Polarized Electrons

et al. 1989

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“…which is a similar expression as describing the capture of spin polarized electrons [11,12]. In this context we are interested in the orientation (k = 1) and from arguments of symmetry one gets only a non zero component "p~ when a quantization axis perpendicular to the scattering plane is used.…”

Section: P=pi|174mentioning

confidence: 96%

Nuclear polarized7Li and14N ions via ion beam surface interaction at grazing incidence

Winter

Andrä

1979

Z Physik A

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“…The authors guessed therefore by comparison with an electrostatic ion-atom interaction model [12] that the production of orientation occurs at distances of at least 0.2~).3 nm from the surface. Actual calculations of electron capture for H-n=2 [13] and n=3 [14] in the high velocity limit are in accordance with non hydrogen-like Stokes parameters when using a minimum distance rc of about 0.35 nm for the anisotropic capture. Coupling of a PCSI-calculation to this initial interaction yields a similar variation of Stokes parameters as observed in our experiments, although the surface field was not specified [15].…”

Section: Introductionmentioning

confidence: 65%

Influence of the surface electric field in ion-beam-surface interaction at grazing incidence

Fröhling

Andrä

1985

Z Physik A

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We have measured the polarization of light emitted after ion surface scattering at small angle of incidence. The measurements are carried out with H § H~--and He § under UHV-conditions with mono-and polycrystalline targets. We explain the typical variation of the polarization as "post collision Stark interaction" (PCSI) in the surface electric field, which can force transitions between nearly degenerate terms. The electric field is composed of two different contributions, a strong but short range surface field which is "seen" by atoms and ions and a long range but weak field due to the image charge which is "seen" to first order only by ions. The influence of the electric field on H-Balmer radiation is negligible at typical survival distances rs>0.35 nm. But in contrast to H-atoms He § feel the additional influence of the image field leading to a strong alteration of the polarization of the emitted light. The polarization of the Balmer-radiation stemming from Coulomb exploding Hi-beams is observed to be modified by the electric field of the "spectator proton".

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Production of high circular polarization by ion surface scattering of ferromagnets

Cited by 20 publications

References 7 publications

Polarized Light Emission after Grazing Ion-Surface Scattering Due to Capture of Spin-Polarized Electrons

Polarized Light Emission after Grazing Ion-Surface Scattering Due to Capture of Spin-Polarized Electrons

Nuclear polarized7Li and14N ions via ion beam surface interaction at grazing incidence

Influence of the surface electric field in ion-beam-surface interaction at grazing incidence

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