2012 Annual Report of the IUCr Commission on Magnetic Structures
The Commission on Magnetic Structures (CMS) of the IUCr was established by the General Assembly in 2011 at the XXII IUCr Congress in Madrid Spain. At the beginning of 2012, the membership of the commission included Jane Brown (France), Branton Campbell (USA), Laurent Chapon (France), Daniel Litvin (USA), Vaclav Petricek (Czech Republic), Alexander Pirogov (Russia), Vladimir Pomjakushin (Switzerland), Juan Rodriguez-Carvajal (France), Taku Sato (Japan) and Wieslawa Sikora (Poland), with Manuel Perez-Mato (UPV/EHU, Spain) and Teresa Fernandez-Diaz (Institut Laue Langevin, France) of the Commission on Neutron Scattering as consultants. In May, Branton Campbell was appointed as commission chair after Laurent Chapon left to take on a new assignment at the ILL. In December, Harold Stokes (BYU, USA) and Mois Aroyo (UPV/EHU, Spain) were appointed as new consultants to the commission.
The scope of our commission’s efforts encompass a broad range of magnetic structure types, including commensurate magnetic structures, modulated and otherwise aperiodic magnetic structures, low-dimensional magnetic structures, disordered magnetic structures, etc. Our formal objectives are listed at http://www.iucr.org/iucr/commissions/magnetic-structures.
In 2012, the commission reviewed and approved the extensive Magnetic Group Tables (almost twelve thousand pages of tabulated data and graphics) prepared by Daniel Litvin for online publication by the IUCr. The tables include magnetic point groups in 1, 2 and 3 dimensions, magnetic space groups in 1, 2 and 3 dimensions, magnetic Frieze groups, magnetic rod groups and magnetic layer groups. The data presented for each group includes graphical and tabulated information following the format of the International Tables of Crystallography Volume A, and also includes standard sets of coset representatives, maximal subgroups of index , and a comparison of Belov-Neronova-Smirnova and Opechowski-Guccione symbols. The tables are accompanied by a 100-page book, which contains examples that guide the user in the interpretation and use of each type of table. This monumental work took many years to complete, and is of great value to all who work with magnetic symmetry and/or magnetic structures. We thank Prof. Litvin for the rare passion that led him to undertake such a project.
The commission conducted a review of the coordinate systems used to describe magnetic structures, and of the refinement packages that implement each one. The report is available on the commission wiki at http://cmswiki.byu.edu/wiki/Magnetic_Coordinates.
Commission member Wieslawa Sikora (Poland) has been appointed to serve on the International Program Committee for the 2014 IUCr Congress in Montreal.
A three-day satellite meeting on Magnetic Symmetry and Structure, to be associated with the next IUCr Congress, is under consideration. This meeting would be cosponsored by the Commission on Magnetic Structures, the Commission on Mathematical and Theoretical Crystallography, and the Commission on Neutron Scattering.
A schedule of meetings of interest to members of the commission was set up on the commission website at http://www.iucr.org/resources/commissions/magnetic-structures/meetings.
Considerable correspondence was focused on the proper description of a magnetic structure. We have considered three primary description types: the supercell description, the wave description, and the representational (group-theoretical) description. Each description type has a distinct parameter set, which if treated in a fully general way, can be converted into any of the other descriptions. Having standards for the various descriptions and their interconversions would make the communication of magnetic structures much more reliable.
Commission members gave featured presentations, developed workshop components, and organized or hosted workshops and microsymposia at a variety of meetings in 2012. These were not specifically organized under the auspices of the commission, but substantially furthered its objectives of promoting magnetic neutron scattering and magnetic structure determination.
- Magnetic Neutron Diffraction Course (Ural Federal University, Russia, March-June, Alexander Pirogov)
- JANA half-day workshop at the colloquium of the Czech and Slovak Crystallographic Association in Klatovy, Czech Republic (12 June 2012, Michal Dusek and Vaclav Petricek).
- Tutorial on Magnetic Structure Determination (Korea University of Technology and Education, Alexander Pirogov)
- 9th International Workshop on Polarised Neutrons in Condensed Matter Investigations (Paris, France, 2-5 Jul, Laurent Chapon)
- 14th ad-hoc JANA 2006 workshop on Magnetic Structures (Prague, Czech Republic, 15-16 Oct, organized and hosted by Michel Dusek and Vaclav Petricek)
- ORNL Workshop on Magnetic Structure Determination (Oak Ridge National Lab, USA, 17-20 Oct, Juan Rodriguez-Carvajal)
- 13th European Powder Diffraction Conference (Grenoble, France, 28-31 Oct, Juan Rodriguez-Carvajal and Laurent Chapon).
Branton J. Campbell