P112 1 /m

1. l s s l (I) Why a neutron diffraction studyon single crystal ? Transverse modulation amplitudes b P1121/m P21nm l l l s s l s s s s s l l s l l s s s l s s l s s s s s l l l l l l l l s s s s s l s s s s s l l Mn4+ Mn3+ Neutron Diffraction on a Pr0.60Ca0.40MnO3 twinned single crystal : A. Daoud-Aladine, et al. Phys. Rev. Lett 89, 97205 (2002) Synchrotron powder diffraction on La1/2Ca1/2MnO3: P. Radaelli et al. Phys. Rev. B 55, 3015 (1997)

2. Superlattice peaks (triangles) (I) Why a neutron diffraction studyon single crystal ? Possibly up to 6 domain contributions Twinned CrystalDiffraction plane at T<TCO Powder diffraction at T<TCO Max=50000 !! 5,6 3,4 b* 1,2 a* Pr0.60Ca0.40MnO3 BM16-ESRF Q(Å-1) Superstructures q=(0 ½ 0) ( 1 -1 0)1 (-1 -1 0)2 ( 1 1 0)3 (-1 1 0)4 ( 0 0 2)5 ( 0 0 2)6 only 10 up to 14 groups of superstructure reflections Synchrotron powder diffraction on Pr0.60Ca0.30MnO3: D. E. Cox et al. Phys. Rev. B 57, 3305 (1998) Basic structure peaks of different orthorhombic domains overlap (circles)