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Magnetische Streuung

Unterschied zu nuklearer Streuung : Formfaktor, Polarisationsfaktor. Magnetische Streuung. Formfaktor. Bestimmung von Formfaktoren: polarisierte Neutronen. Atomgitter. Magnetisches Gitter. Ferromagnet. Antiferro- magnet.  Überstruktur - reflexe. T N =122K.

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Magnetische Streuung

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  1. Unterschied zu nuklearer Streuung: Formfaktor, Polarisationsfaktor Magnetische Streuung

  2. Formfaktor Bestimmung von Formfaktoren: polarisierte Neutronen

  3. Atomgitter Magnetisches Gitter Ferromagnet Antiferro- magnet Überstruktur - reflexe

  4. TN=122K In 1951 Shull showed the magnetic structure of the MnO crystal, which led to the discovery of antiferromagnetism (where the magnetic moments of someatoms point up and some point down).

  5. GdCu2 TN= 42 K M [010] TR= 10 K q = (2/3 1 0) Magnetic Structure from Neutron Scattering Rotter et.al. J. Magn. Mag. Mat. 214 (2000) 281

  6. 4% Ga doped FeGe2 Magnetic Diffraction using Laue Method (LADI – ILL) This material undergoes a number of trans- itions and below 180K it locks into a non- harmonic spiral phase with a propagation vector of exactly 1/10. This gives rise to additional Bragg-peaks, which are shown in the second picture.

  7. NdCu2

  8. mehrere Kristallite (ca 120° verdreht) τ 3τ 5τ l

  9. AF2 Pattern T=4.1K H=0T

  10. NdCu2 Magnetic Structures at T=0

  11. Pattern T=0 k 0.4 0.6 0.8 1.0 h AF1    3τ 5τ τ=(0.6 0 0) F1  2τ τ=(0.6666 0 0) 2τ F2  2τ τ=(0.625 0 0)  F3

  12. Komplexere Strukturen F2

  13. GdCu2In nichtkollineare Struktur(mcphase) I(κ) [counts] |κ|[Å-1]

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