Schwinger and anomalous scattering of neutrons from CdS

Felcher, G. P.; Peterson, S. W.

doi:10.1107/s0567739475000149

Cited by 21 publications

(12 citation statements)

References 8 publications

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“…It was then experimentally observed in vanadium and CdS single crystals by C. G. Shull [8,9]. Later it was used by Felcher and Peterson to determine the absolute configuration of a CdS single crystal [10]. [11] and have been inverted for the right-handed structure.…”

Section: Introductionmentioning

confidence: 99%

Absolute crystal and magnetic chiralities in the langasite compound Ba3NbFe3Si2O14 determined by polarized neutron and x-ray scattering

et al. 2020

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We present a combined polarized neutron and x-ray scattering study on two enantiopure langasite single crystals aimed at the determination of their absolute structural and magnetic chiralities and the coupling between them. Our respective data sets unambiguously reveal two samples of opposite structural chirality, where the magnetic handedness is pinned by the structural one. Simple energy considerations of the magnetic exchange and single-ion anisotropy parameters reveal that it is not the Dzyaloshinskii-Moriya interaction but the local single-ion anisotropy on a triangular plaquette which plays a key role in stabilizing one of the two magnetic helices.

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Section: Introductionmentioning

confidence: 99%

Absolute crystal and magnetic chiralities in the langasite compound Ba3NbFe3Si2O14 determined by polarized neutron and x-ray scattering

et al. 2020

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“…2a). This is analogous to the Mott asymmetry (Tolhoek, 1956) observed in the scattering of an electron by the electric field of a nucleus, or to the Schwinger (1948) scattering (see a recent review by Felcher & Peterson, 1975), which is similar to the Mott assymetry but concerns neutrons instead of electrons (Fig. 2b).…”

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confidence: 99%

“…The first term is independent of them and corresponds to the effects shown in Fig. 2; the Schwinger scattering amplitude (Felcher & Peterson, 1975) is similar, if considered in the limiting case where the scatterer is a neutral atom much smaller than the wavelength [the electronic radius 2~ which appears in (21) is then replaced by the atomic radius]. …”

mentioning

confidence: 99%

“…For some applications it is important to define unambiguously the sign of the imaginaries. As discussed by Ramaseshan, Ramesh & Ranganath (1975) and by Felcher & Peterson (1975)two conventions are commonly used: physicists and neutron diffractionists put the minus sign in front of the frequency x time product in the expression of the waves, and they take ko) --k(f ) as the scattering vector, while X-ray crystallographers usually put the opposite sign in front of the frequency x time product and use an opposite scattering vector. For consistency with Berestetski et al (1972) and other text books we use the first convention.…”

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confidence: 99%

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Diffraction of X-rays by magnetic materials. I. General formulae and measurements on ferro- and ferrimagnetic compounds

Bergevin¹,

Brunel²

1981

Acta Cryst Sect A

237

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The calculation of the amplitude of X-rays scattered by a magnetically ordered substance, carried out in the relativistic quantum theory (i.e. taking the spin into account), is detailed. The effect of the orbital momentum is described in an appendix. The practical formulae dealing with the polarization of the beams are given both in a simple form for the usual experiments and in a complete form, using the Stokes vectors, for the most general case. The experiments show a change in the intensity of the X-rays diffracted by a ferromagnetic (pure iron) or a ferrimagnetic (zinc-substituted magnetite) powder when the magnetization, perpendicular to the diffraction plane, is reversed. The relative values of these intensity changes range from 10 -4 to 5 x 10 -3 and agree in sign and magnitude with the predictions. They are proportional to the spin-density structure factor multiplied by the imaginary part of the chargedensity structure factor; the large anomalous scattering of the Cu Ka radiation in the iron-containing samples is used in the present experiments. moment associated with the spin does interact with the magnetic field of the radiation (Fig. 1). This effect can Driving force Reradiation-eE E -e E-dipol.-eE H -e ~ H-quadr. E grad/~.H --e~ffj ~C_.,~ ~ ~H $ E-dipol. IntroductionX-ray diffraction is usually interpreted through the Thomson scattering mechanism, i.e. the interaction between the electromagnetic radiation and the charge of the electrons. X-rays therefore seem to give information about the charge density only and not about the spin density. If one examines the phenomenon more thoroughly, it appears that the electronic spin also plays some role; the magnetic 0567-7394/81/030314-11 $01.00Tor qUeHx/ z ~; ~H H-dipol. be treated with relativistic quantum theory. The Klein & Nishina (1929) formula for the Compton effect takes this effect into account, but only implicitly since it concerns mean values taken over all spin states. In relativistic theory space and spin wave functions cannot be separated as they can be in the nonrelativistic limit. A perturbation on the movement of an electron has an effect which depends upon the spin. During the collision with a photon of momentum k(0 (k¢f) after collision) the electron is accelerated. One may admit that the effect of this acceleration depends upon the direction of the spin by some term of the order of I k(f) -k(0 I/mc, which expresses the relativistic character of the acceleration undergone by the electron (Fig. 2a). This is analogous to the Mott asymmetry (Tolhoek, 1956) observed in the scattering of an electron by the electric field of a nucleus, or to the Schwinger (1948) scattering (see a recent review by Felcher & Peterson, 1975), which is similar to the Mott assymetry but concerns neutrons instead of electrons (Fig. 2b). These effects can also be compared to the spin-orbit coupling (Fig. 2c), the magnitude of which is still determined by the ratio I pl/mc (p is the electron momentum). One should not forget that these comparisons do not account f...

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“…In addition to anomalous scattering, there is also Schwinger scattering 29 (interference between nuclear and electronic potential) which produces a right-and left-handedncss to some scattering. This also may be used to determine phase.…”

Section: Fur 9 a Tof Laue Diffraction Instrument For Use On Wnrmentioning

confidence: 99%

Set of thermal neutron-scattering experiments for the Weapons Neutron Research Facility

Brugger¹

1975

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Schwinger and anomalous scattering of neutrons from CdS

Cited by 21 publications

References 8 publications

Absolute crystal and magnetic chiralities in the langasite compound Ba3NbFe3Si2O14 determined by polarized neutron and x-ray scattering

Absolute crystal and magnetic chiralities in the langasite compound Ba3NbFe3Si2O14 determined by polarized neutron and x-ray scattering

Diffraction of X-rays by magnetic materials. I. General formulae and measurements on ferro- and ferrimagnetic compounds

Set of thermal neutron-scattering experiments for the Weapons Neutron Research Facility

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