Download presentation

Presentation is loading. Please wait.

Published byJessica Wyatt Modified over 2 years ago

1
Magnetic Diffraction Difference to nuclear scattering: Formfactor... no magnetic signal at high angles Polarisationfactor... only moment components normal to κ contribute

2
Bestimmung von Formfaktoren: polarisierte Neutronen Formfaktor

3
Atomgitter Magnetisches Gitter Ferromagnet Antiferro- magnet Überstruktur - reflexe

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

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

6
Magnetic Diffraction using Laue Method (LADI – ILL) 4% Ga doped FeGe 2 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) l τ 3τ3τ 5τ5τ

9
AF2 Pattern T=4.1K H=0T

10
NdCu2 Magnetic Structures at T=0

11
Pattern T=0 h 0.40.60.81.0 AF1 F1 F2 F3 τ=(0.6 0 0) 5τ5τ3τ3τ τ=(0.6666 0 0) τ=(0.625 0 0) 2τ2τ 2τ2τ 2τ2τ k

12
Komplexere Strukturen F2

13
|κ|[Å -1 ] I(κ) [counts] nichtkollineare Struktur(mcphase) GdCu 2 In

Similar presentations

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google