"Nachweis antiferromagnetischer Fernordnung mittels Neutronendiffraktion"
"Determination of long range antiferromagnetic order by powder neutron diffraction"
Antiferromagnetic (AFM) ordering of Mn spins in manganese sulfide MnS or manganese oxide MnO will be determined by powder neutron diffraction. These compounds crystallize in a rock salt face centered cubic crystal structure. Manganese sulfide MnS shows a transition to the AFM state with the propagation vector k=[1/2 1/2 1/2] at Neel temperature about 150K. The Mn-spins forming planes perpendicular to the body diagonal are ferromagnetically aligned, whereas the spins in the neighboring planes are antiparallel.
During the practicum we will try to reproduce the one of the neutron diffraction experiments performed during 1946-1951 for which C.G. Shull was honored with the Nobel Prize in 1994. We will perform neutron diffraction experiment with MnS using powder diffractometer HRPT/SINQ. From the analysis of the nuclear and magnetic Bragg peak intensities and positions we will verify the crystal and magnetic structures of manganese sulfide and determine the size of the magnetic moment on manganese.
Note: The practicum is performed during only one day at PSI. To perform the experiment effectively and analyze the experimental data it is necessary to have basic theoretical background on mathematical description of crystal structure and diffraction (reciprocal space, Brillouin zone, structure factor, etc.)
- Description with the tasks to do at the end (new, English)
- Presentation of the practicum with updated tasks to do at the end (newest, English)
- Praktikum tasks
- Beschreibung des Praktikums (old but detailed)
Some relevant lectures (by V. Pomjakushin).
" Magnetic symmetry for multi-k structure models ", Workshop "Workshop on topology in Magnetic Materials ", Nov 23, 2022, Herzberg
"Magnetic order from neutron diffraction experiments: applications of representation decomposition and Shubnikov symmetry", and "Diffraction at swiss spallation source SINQ"
IUCr Congress Satellite Workshop on the Role of Magnetic Symmetry in the Description & Determination of Magnetic Structures, 14-16 August, 2014, Brockhouse Institute for Materials Research, McMaster University, Hamilton, Canada
"Magnetic Neutron Diffraction" lecture (1½h) given at workshop Neutron Scattering and Imaging for Newcomers, (14th to 17th August 2019, Vienna University of Technology). This satellite workshop was preceeding the ECM32 congress - 32nd European Crystallographic Meeting (18. – 23. 08. 2019, University of Vienna)
"Symmetry constraints in solving magnetic structures by neutron diffraction: Representation analysis and Shubnikov groups", and "Introduction to experimental neutron diffraction" (41 Mb).
Lectures given at the MOTT PHYSICS BEYOND THE HEISENBERG MODEL Master Class, October 26th to 27th, 2013, Paul Scherrer Institut, Villigen, Switzerland".