2019 Annual Report of the IUCr Commission on Magnetic Structures
The commission was busy in 2019 in its effort to disseminate standards for the determination and communication of magnetic structures. Key activities include organizing and executing a ten-day school on magnetic crystallography, organizing sessions relevant to magnetic-structure research for the program of the upcoming IUCr congress, and developing features to support magnetic structures in widely-used crystallographic software.
53rd International School of Crystallography
The commission organized and conducted the 53rd course of the International School of Crystallography at the Ettore Majorana Research Foundation in Erice, Italy, on the subject of Magnetic Crystallography (https://crystalerice.org/2019/welcome.php), during the ten days from May 31st to June 9th of 2019.
Commission members who participated in organization and/or lectures and workshops:
- Branton Campbell (Brigham Young University, USA) – science director
- Maria Teresa Fernandez-Diaz (Institut Laue-Langevin, France) – science director
- Manuel Perez-Mato (Unversidad del Pais Vasco, Spain) – science director
- Maxim Avdeev (ANSTO Australian Center for Neutron Scattering, Australia)
- Ovidiu Garlea (ORNL Neutron Scattering Division, Oak Ridge, USA)
- Margarida Henriques (CAS Institute of Physics, Prague, Czech Republic)
- Vaclav Petricek (CAS Institute of Physics, Prague, Czech Republic)
- Juan Rodriguez-Carvajal (Institut Laue-Langevin, Grenoble, France)
- Taku Sato (Tohoku University, Tohoku, Japan)
- Andrew Wills (University College London, London, UK)
- Oksana Zaharko (Paul Scherrer Institut, Villigen, Switzerland)
Others who contributed lecture and workshop presentations:
- Laurent Chapon (Diamond Light Source, Didcot, UK)
- Luis Elcoro (University of the Basque Country, Bilbao, Spain)
- Oscar Fabelo (Institut Laue-Langevin, Grenoble, France)
- Dmitry Khalyavin (RAL ISIS Facility, Didcot, UK)
- Harold Stokes (Brigham Young University, Provo, USA)
- Robert Von Dreele (ANL Advanced Photon Source Argonne, USA)
The local organizing team was led by Annalisa Guerri (University of Florence, Italy) and Paola Spadon (University of Padova, Italy), and included computing and technical support from Andrea Giaccherini (University of Florence, Italy), Andy Stewart (University of Limerick, Ireland), and Erin Davis (USA).
The school was advertised internationally, with a special emphasis on reaching out to researchers in countries that are not typically well represented at such meetings. There were no restrictions on geographical affiliations of the participants. From among the roughly 100 applicants, 64 participants (not including the presenters) were selected based on their preparation and ability to benefit from attendance; this was the maximum number that facility-space limitations allowed. The participants and presenters came from 25 different nationalities and country affiliations, more than half of which were outside of Western Europe or North America. There were significant numbers from each of Russia and Eastern Europe, Asia, South America, and India. More than one third of the attendees were women.
The magnetic-crystallography program was organized to address key advances in magnetic-structure research, as well as the foundational and state-of-the-art of theoretical, experimental, and computational capabilities that made these advances possible. The school included a roughly 50/50 combination of lectures and hands-on workshops. Three hours of workshops were held each morning, with two sessions conducted in parallel. The state-of-the art computational tools represented in the workshops included FullProf, JANA 2006, SARAh, the Bilbao Crystallography Server, the ISOTROPY Software Suite, GSAS-II, and TOPAS. Both introductory and advanced tutorial exercises were provided, in order to fully engage beginners and experts alike. Three hours of lectures were presented each afternoon. Topics included the experimental determination and communication of magnetic structures, the theoretical and mathematical foundations of magnetic symmetry and representational analysis, and a wide variety of applications. Each of the 17 presenters, in addition to contributing a lecture, also provided lecture notes in manuscript form. The technical program ended with a one-hour panel discussion of questions submitted by the participants.
Of 40 submitted participant abstracts, 10 were selected for oral presentations (22 minutes or 15 minutes), including Shivani Sharma (JNCASR, Bengaluru, India), Anna Matveeva (Petersburg Nuclear Physics Institute, Gatchina, Russia), Jose Luis Garcia-Munoz (ICMAB-CSIC, Barcelona, Spain), Stephanie Gneuwuch (U. Maryland, USA), Anuradha Vibhakar (U. Oxford, UK), Elena Solana Madruga (U. Edinburgh, UK), Stefanie Siebeneichler (Stockholm U., Sweden), Fernando Pomiro (U. Warwick, UK), Claire Colin (Institut Néel, U. Grenoble-Alpes, France), and Francoise Damay (Laboratoire Léon Brillouin, Gif-sur-Yvette, France). The two poster sessions for participant research were also of very high quality and were well attended during the school. Three of these posters were selected by a panel of judges for awards, which were presented during the closing ceremony, which included Premakumar Yanda (JNCASR, Bengaluru, India), Rebecca Scatena (U. Bern, Switzerland), and Guru Khalsa (Cornell U., USA).
To facilitate interaction between and among the participants and presenters, the school included a rich social program, which included several social dinners, an evening with local musicians and performers, excursions to historical sites in the region, and daily lunch and coffee breaks. In the relaxed atmosphere, the organizers attempted to become personally acquainted with each participant. We are confident that the school initiated many long-term friendships and collaborations.
Preparations for the IUCr Congress
In preparation for the upcoming IUCr Congress in Prague, the commission met online to brainstorm, select, and prioritize topics potential topics. Then, in May 2019, Oksana Zaharko, our representative to the International Planning Committee, traveled to Prague to negotiate the final program. Her outstanding efforts and negotiation skills made it possible to organize 15 sessions with magnetic-structure themes or components, among which 9 microsymposia and 3 keynote lectures were sponsored or co-sponsored by the commission (listed below). Oksana’s invaluable service on the IPC is greatly appreciated by all.
- Magnetic structures of novel and functional materials (MS-30)
- Structural, electronic and magnetic ordering: from fundamental physics to functionality (MS-38)
- New applications of coherent scattering (MS-40)
- Frustrated magnetic order and emerging science (MS-45)
- Molecular magnets and metal-organic frameworks, including quantum crystallography approaches (MS-51)
- Magnetic structures at extreme conditions and in extreme samples (MS-61)
- Symmetry aspects of magnetic order and magnetic properties (MS-68)
- Methods and software developments for magnetic-structure analysis (MS-79)
- Topological magnetic order and quasiparticles (MS-87)
- The science of symmetry breaking, Stokes Harold (KN-35)
- Structural flexibility and disorder in functional materials, Andrew Goodwin (KN-3)
- Quantum crystallography and spintronic materials, Macchi Piero (KN-15)
For the IPC meeting in Prague, Oksana, together with B.J. Campbell, J. M. Perez-Mato, and T. Sato, submitted a manuscript on “Magnetic Structure Research, Future and Future Trends”, which was subsequently published in Materials Structure 26 (2), 97-100 (2019).
The Bilbao Crystallographic Server upgraded the MTENSOR program to include magnetic phases, as reported in Acta Cryst. (2019) A75, 438-447. It now calculates the symmetry-adapted forms of physical-property tensors that include magnetic properties. Also, over one hundred entries have been added to the MAGNDATA database of magnetic structures, bringing the total number to about 700.
The first version of FullProf (version 7.00) able to refine magnetic structures (powder and single crystals) having up to three independent modulations within the superspace formalism was distributed in May 2019. The symmetry constraints on modulation functions was fully implemented for an arbitrary set of propagation vectors and harmonics. Spherical coordinates can be used to describe modulation amplitudes facilitating the use of extra-constraints beyond symmetry. Presently, only magnetic modulations are available, though displacive, occupational and ADP modulations will be also implemented in the future. The program outputs a magnetic P1-symmetry CIF file that can be directly read by VESTA to visualize a user-selected supercell. A conventional modulated mCIF file is also output with the refined magnetic structure. This file can be read by JMOL/MVISUALIZE to plot the magnetic structure.
Le Bail fits using superspace groups was also fully implemented in FullProf with an output adequate to perform, in a second stage, a simulated annealing run working with the full powder profile to solve magnetic structures ab initio. All modulation functions are included in the simulated annealing method with all kind of constraints compatible with the symmetry.
The program mCIF_to_PCR from the Bilbao Crystallographic Server has been extended to accommodate incommensurate structures with superspace-group symmetry. After importing a CIF from ISODISTORT, mCIF_to_PCR automatically allows one to prepare the input file for FullProf using a superspace groups in whatever setting.
The program WinPLOTR-2006 in the FullProf Suite has been modified in order to identify the different kind of reflections: nuclear, magnetic of mixed (up to six integer indices), when using superspace description.
SARAh was recently launched as a webApplication in order to stabilize its development base and move away from issues related to legacy Windows operating systems. As part of a goal to bring representational analysis calculations closer to the two-colour groups, the web version now determines isotropy groups and related magnetic point groups of the little group Gk for and their basis vectors, as well as those of the kernel calculations. Calculations can be done for commensurate and incommensurate structures alike.
GSAS-II now fully supports magnetic structures, including those with one incommensurate modulation. The search for a correct description of a magnetic structure is simplified in GSAS-II where a special version of the k-SUBGROUPSMAG tool from the Bilbao Crystallographic Server is called with the parent chemical space-group operations, selected k-vectors, and some option flags. The result is parsed by GSAS-II to extract the generated magnetic space groups, transformation matrices, origin shift vector, conjugacy classes (if any), and supergroup lists. GSAS-II also examines the magnetic atom positions to determine if any or all can carry a nonzero moment, flagging those space groups with atoms that can.
JANA2006 performs representation analysis for and commensurate cases based on the irreducible representation data published by H. T. Stokes, B. J. Campbell and R. Cordes, Acta Cryst. (2013). A69, 388-395. This allows it to use the same symbols as in ISODISTORT. The procedure for importing the models from ISODISTORT was considerably improved. Furthermore, the new version allows parallel refinement of several models. The graphic interface for the new Jana2020 has also been further developed.
In the ISOTROPY Software Suite, the symmetry-allowed forms of Wyckoff sites are now presented for magnetic and non-magnetic incommensurate structures. Magnetic and non-magnetic incommensurate symmetry groups have been partially implemented in FINDSYM and ISOCIF. When finished, it will be possible to detect the actual or pseudo symmetry (with tolerances on atomic parameters and Fourier coefficients) of an incommensurate magnetic structure. The magnetic superspace groups (MSSGs) with up to three modulations have been fully enumerated. All modulation-capable software tools have been updated to detect/present the correct MSSG number and symbol.
The members of the commission actively promotes the presentation of high-quality research on magnetic structures at a broad variety of international conferences, workshops, and schools. The commission supports a variety of scientific meetings each year through formal sponsorship, and with its members and consultants participating in featured lecture presentations, workshop tutorials, organization and chairing of conference sessions, and the presentation of lecture courses. Highlights from 2019 include the following:
- Current Trends and Future in Crystallography, satellite meeting of the IUCr International Planning Commission meeting, 14 May 2019, Prague Congress Centre, Praha, Czech Republic. (Presenter: O. Zaharko, Manuscript co-authors: O. Zaharko, B.J. Campbell, J. M. Perez-Mato, T. Sato)
- International School of Crystallography (53rd course) on “Magnetic Crystallography”, 31 May – 09 June, 2019, Ettore Majorana Foundation and Centre, Erice, Sicily, Italy. Directly organized by the commission. (Scientific Directors: B. Campbell, M. Fernandez-Diaz, M. Perez-Mato; Lecturers: M. Avdeev, O. Garlea, M. Henriques, V. Petricek, J. Rodriguez-Carvajal, T. Sato, A. Wills, O. Zaharko)
- Neutron Summer School, session on “Magnetic structure determination from neutron powder diffraction”, 19-21 June 2019, Peking University, Beijing, China. (Lecturer: M. Avdeev)
- International School on Crystallographic Groups & Their Representations, and the subsequent Workshop on Topological Insulators, 1-7 Jul 2019, International Center for Quantum and Molecular Structure, Shanghai University, Shanghai, China. (Organizer and Lecturer: M. Aroyo)
- American Crystallographic Association Meeting, 20-24 July 2019, Covington, Kentucky, USA. Session on “Magnetic, quantum, and electronic correlated materials”. Sponsored by the Commission (Co-chair: B. Campbell)
- 32nd European Crystallographic Meeting, satellite workshop on “Neutron Scattering and Imaging for Newcomers”, 14-17 Aug 2019, Vienna University of Technology and University of Vienna, Vienna, Austria. (Lecturers: V. Pomjakushin, M. Henriques, V. Petricek)
- Workshop on Symmetry and Superspace Approach to Modulated Crystal Structures, Oak Ridge National Laboratory, USA, 23-24 Oct 2019. (Lecturers: M. Henriques, V. Petricek, B. Campbell)
- Workshop on Magnetic Structure Determination from Neutron Diffraction Data, 21–23 Oct 2019, Oak Ridge National Laboratory, USA. (Co-Organizer and Lecturer: O. Garlea)
- Masters course on “Neutron diffraction on functional and magnetic materials”, Oct-Dec 2019, Ural Federal University, Ekaterinburg, Russia. (Organizer and Lecturer: A. Pirogov)
- 37th Ad Hoc Workshop on Jana2006 on the topic of “Magnetic structures”, 14-15 Nov 2019, Institute of Physics, Praha, Czech Republic. (Organizers and Lecturers: V. Petricek, M. Henriques)
- Asia-Oceania Neutron Scattering Conference, 16-19 Nov 2019, Kenting, Taiwan. (Organizers and Lecturers: M. Avdeev, T. Sato)
- 11th School of the Argentinean Association of Crystallography on “Structural and Magnetic Rietveld Refinement of X-ray and neutron diffraction”, 18-22 Nov 2019, Bariloche, Argentina. Sponsored by the commission, and supported by an IUCr Visiting Professorship to O. Fabello. (Lecturers: O. Fabello, J. Rodriguez-Carvajal)
Commission membership: Branton Campbell (Chair, USA), Maxim Avdeev (Australia), Maria Teresa Fernandez-Diaz (France), Ovidiu Garlea (USA), Margarida Henriques (Czech Republic), J. Manuel Perez-Mato (Spain), Juan Rodriguez-Carvajal (France), Taku Sato (Japan), Andrew Wills (UK), and Oksana Zaharko (Switzerland).
Commission consultants: Mois Aroyo (Spain), J. Campo (Spain), Danny Litvin (USA), Alexander Pirogov (Russia) and Wieslawa Sikora (Poland).