2016 Annual Report of the Commission on Magnetic Structures
The voting membership of the commission, which did not change in 2016, includes Branton Campbell (Chair, USA), Andrea Cornea (Italy), Daniel Litvin (USA), Manuel Perez-Mato (Spain), Vaclav Petricek (Czech Republic), Alexander Pirogov (Russia), Vladimir Pomjakushin (Switzerland), Juan Rodriguez-Carvajal (France), Taku Sato (Japan) and Wieslawa Sikora (Poland). The commission’s consultants include: Mois Aroyo (Spain), Maria Teresa Fernandez-Diaz (Institut Laue Langevin, France), Harold Stokes (USA), and Andrew Wills (UK).
On 08 Feb 2016, Alexander, Andrea, Andrew, Branton, Manu, Vaclav, Vladimir, Taku, and Wieslawa convened an internet-video meeting to prioritize the proposed IUCr Congress 2017 sessions and to prepare a list of potential chairs for each session. The resulting list emphasized diversity and also provided opportunities for co-sponsorship with other commissions. Plans to complete the magCIF dictionary were set in motion, and strategies for encouraging its widespread adoptions were discussed. Manu highlighted a new tool on the Bilbao Crystallographic server that converts between OG and BNS settings of magnetic space groups. The magCIF working group also met on 08 Feb to discuss a collaboration with COMCIFS to convert our custom-markup version of magCIF into a proper DDLm dictionary. Recent progress on the support of OG settings was reviewed, and a number of tags from the prototype dictionary were abandoned, revised, or converted to progress-pending place holders. Discussion on new tags for communicating symmetry constraints was initiated. Existing tags in the twinCIF dictionary appear sufficient for handling magnetic-domain twinning.
The commission’s 13 Oct 2016 internet-video meeting was attended by Alexander, Andrea, Branton, Danny, Juan, Manu, Vaclav, Vladimir, Taku, and Wieslawa. Taku described volatility in the list of confirmed session chairs, which continues to require attention. Because Hyderabad appears to be a daunting summer destination for some, the commission determined to devote extra effort to advertising the meeting. Potential changes to commission membership and leadership were discussed; excellent recommendations were received from several national committees, and a vote is planned for late spring 2017. Summer efforts to finalize the magCIF dictionary were reviewed. Branton and Manu provided anecdotal evidence that the historical BNS and OG magnetic-space-group symbols can be an obstacle to understanding for beginners, and suggested that a new international standard for MSG symbols might be helpful, particularly where the magnetic point group is concerned. It was proposed that the ISO-MAG tables of magnetic space groups by Stokes and Campbell should be subject to a formal IUCr review. Future priorities include (a) a representational-analysis CIF dictionary, (2) descriptions of low-dimensional and short-range magnetic order, (3) increased efforts to educate the community on the proper description of magnetic structures. Congratulations are extended to Wieslawa for her recent retirement, and also to Vaclav for receiving the ECA’s Max Perutz prize in 2016!
In April 2016, Taku Sato, the commission’s representative to the International Planning Committee of the 2017 IUCr Congress, traveled to Hyderabad to negotiate the final program. His tireless efforts resulted in many sessions with strong magnetic-structure themes, including two microsymposia and a keynote lecture sponsored by the commission, five microsymposia co-sponsored with other commissions, and at least five other sessions created without our direct support. His service on the IPC is greatly appreciated.
Branton and the magCIF working group, in collaboration with James Hester (COMCIFS chair), made extensive revisions to the magCIF dictionary in preparation for the COMCIFS review. Most of the changes required for DDLm conversion were straightforward, though some required changes to core tag names and were therefore quite painful due to loss of some backwards compatibility with numerous prototype files (e.g. those presented on the MAGNDATA website). Once the conversion to DDLm was complete, the dictionary was submitted to COMCIFs. Final approval came on 31 Oct 2016. The new dictionary is available on a Github development site now, and will be formatted for the IUCr website early next year, after several existing dictionaries have been retrofitted to DDLm. Ideally, all relevant packages soon be able to exchange final-version magCIF files. Assignments to coordinate with a variety of software developers were delegated to working-group members. The best way to balance the use of OG and BNS is still under discussion – we’ll try to include both where possible. A two-way magCIF-conversion utility that could directly convert between OG and BNS setting is needed, as would a utility for converting between commensurate-supercell and incommensurate-wave description of a commensurate magnetic structure.
A workshop on New Trends in Magnetic Structure Determination (12-16 Dec 2016, Institute Laue Langevin, Grenoble France, https://indico.ill.fr/indico/event/53/overview) was sponsored by the commission, which highlighted much of the new infrastructure for magnetic-structure descriptions developed by the commission during the past five years. The meeting was organized by Juan Rodriguez Carvajal and Oscar Fabelo, and generously supported by the ILL. Lectures and tutorials were given by Laurent Chapon and Juan Rodriguez-Carvajal (FullProf), Vaclav Petricek (JANA), J. Manuel Perez Mato (Bilbao Crystallographic Server), and Harold Stokes and Branton Campbell (ISOTROPY Suite). Of the 60 applicants, 40 were selected to attend. Most participants were accomplished magnetic neutron scatterers aiming to stay abreast of recent developments. The focus of the meeting was on new software capabilities for treating magnetic space-group and superspace-group symmetry, magnetic representation analysis, fully-general magnetic structures, incommensurate magnetic modulations. An underlying theme throughout was the use of the new magCIF format for communicating magnetic-structure information between a variety of structure-analysis programs, visualization packages, and data resources.
Two papers were published in 2016 by the Bilbao Crystallographic Server team describing their MAGNDATA database of over 400 published commensurate and incommensurate structures. Each structure is unambiguously presented with magnetic space-group or superspace-group symmetry in the magCIF format. See S.V. Gallego et al., J. Appl. Cryst. (2016), 49, 1750-1776 and 1941-1956. Any of the stored structures can be immediately visualized and readily imported into a variety of other software packages.
The commission supports a variety of scientific meetings each year through formal sponsorship, direct meeting organization, featured lecture presentations, workshop tutorials, the organization and chairing of conference sessions, and the presentation of lecture courses. Highlights from 2016 include the following:
- Institute of Metal Physics Achievements meeting 28 Mar 2016, Ekaterinburg Russia (lecture by A. Pirogov).
- Crystals 30 Meeting, 29 Mar – 01 Apr 2016, Hobart, Tasmania, Australia (plenary lecture by B. Campbell).
- Institute of Reactor Materials 50-Anniversary meeting, 19 May 2016, Zarechny Russia (lecture by A. Pirogov).
- REXS20016 Conference on Resonant X-ray Elastic Scattering, 13-17 June 2016, Hamburg Germany (invited lecture by J.M. Perez-Mato).
- 3rd International School in Aperiodic Structures, 4-8 July 2016, Antwerp, Belgium (lectures and tutorials by V. Petricek).
- UFOX – Unveiling complex phenomena in Functional OXides, 7-8 July 2016, Unversity of Salerno, Salerno, Italy (lecture by V. Pomjakushin) http://sinq.web.psi.ch/sinq/instr/pomjakushin/doc/pomjakus_ufox16_fin.pdf.
- ACA Satellite Workshop on Magnetic Structure Determination, 22 July 2016, Denver USA (lectures and tutorial by B. Campbell).
- MAGSTR2016 workshop on Symmetry-Based Modeling of Magnetic Structures, 23-26 Aug 2016, Tallahassee Florida, USA (lectures and tutorials by J.M. Perez-Mato and J. Rodriguez-Carvajal). https://conference.sns.gov/event/22/page/5
- ECM-30, “On the fascinating way from an abstract superspace theory to the practical structure analysis of modulated and composite crystal”, Basel, Switzerland, 28 Aug – 01 Sep 2016 (Max Perutz prize lecture by V. Petricek).
- XIII International Conference on Crystal Chemistry of Intermetallic Compounds, 25-28 Sep 2016, Lviv, Ukraine (lecture by V. Petricek).
- New Trends in Magnetic Structure Determination, 12-16 Dec 2016, Institut Laue-Langevin, Grenoble France, (described above).
Branton J. Campbell