A series of one day meetings designed to bring together experts from the multiferroics, magnetoelectrics and ferroelectrics communities with neutron and synchrotron facility users to present the latest developments in this field. The meetings are held at NPL.

Second meeting – 23 September 2011 

A series of presentations were given by leading researchers covering a variety of topics, from fundamental physics of multiferroic switching, to X-ray experimental results and best practice. Other talks focused on the practicalities of using ferroelectrics as computer memory (RAM) and magnetic storage. 

A discussion forum was held during the afternoon, to examine the experimental uncertainties concerning application in situ electric, magnetic and stress fields in x-ray and neutron experiments. Delegates also debated a wider range issues in materials processing, crystal growth and sample preparation. 

The event was highly successful and brought together many leading researchers in the field for the sharing of ideas and results in an informal setting. 

The following talks were presented: 

• More than one twist: multiferroics and magnetoelectrics beyond the cycloidal mechanism, Paolo Radaelli (University of Oxford).
• In situ neutron and x-ray synchrotron studies of multiferroics, Andrew Bell (University of Leeds).
• Advancing the understanding of multiferroics through resonant x-ray scattering, Peter Hatton (Durham University). 
• In-situ studies of structure and electrical properties of BiFeO3 as a function of temperature and pressure, Bob Freer (University of Manchester). 
• Local and average structures of new leadfree polar materials, Matthew Rosseinsky (University of Liverpool).
• Electric control of magnetic chirality in CuO, Andrew Boothroyd (Oxford). 
• X-ray Resonant Magnetic Scattering of Strain induced Magnetoelectric EuTiO3 films, Simon Brown (ESRF). 
• In situ facilities for ferroelectric and multiferroic materials at ESRF and DIAMOND, Mark Stewart (NPL). 

First meeting – 17 June 2009

The Functional Materials Group at NPL, and the UK-CRG XMaS beamline, based at the European Synchrotron Radiation Facility in Grenoble, France, co-hosted the first UK workshop on X-rays and neutrons in multiferroic research on 17 June 2009. 

The following talks were presented:

• Multiferroics & magnetoelectrics, Neil Mathur (University of Cambridge)
• Electric field control of magnetic order in multiferroic TBMnO3 imaged with circularly polarised X-rays, Des McMorrow (UCL)
• X-Ray scattering techniques to explore in-situ properties of multiferroic materials, Peter Hatton (Durham University)
• Structure and Phase Transitions in Multiferroics: The Case of BiFeO3, Phil Lightfoot (University of St Andrews)
• Dependence of internal stress and hyrostatic pressure on the magnetic ordering in the multiferroic BiFeO3 – PbTiO3, Tim Comyn (University of Leeds)
• Induced multiferroic behaviour in single crystals  of RMO3 Manganites, Geetha Balakrishnan (University of Warwick)
• Stress, E field and B field in-situ measurements, Mark Stewart (NPL) and Paul Thompson (XMaS CRG)

The group ascertained that the main experimental interests in this field focus on the ability to perform in-situ magnetoelectric and piezoelectric measurements. This workshop was a first milestone for the development of fundamental research in the field of multiferroics and x-ray/neutron scattering. 

A series of talks showing recent progress in this field was kicked off by Neil Mathur (University of Cambridge) who gave an introduction to multiferroic, magnetoelectric and ferroelectric phenomena, detailing examples of materials properties such as bismuth ferrite, which is a good room temperature FE. Crystallography studies of this material were presented by Phil Lightfoot (University of St Andrews) and Tim Comyn (University of Leeds), the former using neutron diffraction measurements to determine the atomic structure of the high temperature phases, and the latter investigating the effect of different sample processing techniques on the crystal symmetry. Doping bismuth ferrite with lead titanate results in a mixed phase compound that his strongly ferroelectric and piezoelectric – it is also possible to ‘switch on’ the magnetic ordering by means of an in-situ hydrostatic pressure. 

The use of magnetism to control the polarisation was discussed by Des McMorrow (UCL) who used non-resonant x-ray scattering and x-ray polarimetry to deduce the magnetic structure and domain population of the multiferroic TbMnO3. Resonant x-ray scattering techniques were employed by Peter Hatton (Durham University) to look at the magnetism of a different terbium manganese oxide, TbMn2O5. The magnetic structure refinements using these techniques however, often rely on complimentary neutron studies, and some examples of these in the wider class of manganese oxide materials RMn2O5 were presented by Carlo Vecchini (ISIS). 

Geetha Balakrishnan (University of Warwick) discussed how the non-ferroic SmMnO3 compound could be ‘tuned’ into multferroicity by doping with Yttrium to force the crystallographic structure into the part of the RmnO3 phase diagram occupied by TbMnO3 and DyMnO3 – well known multiferroic compounds. She concluded by presenting neutron scattering data on the frustrated Kagome staircase compounds nickel vanadate and cobalt vanadate – previously studied for their interesting magnetic order, and only recently discovered to be ferroelectric. Since ferroelectricity is known to occur when magnetic ordering breaks inversion symmetry, magnetic insulators with modulated magnetic structures, as found in the vanadates, are ideal candidates for new multiferroic materials. 

The workshop concluded with presentations by Mark Stewart (NPL) on the experimental procedures required to characterise ferroelectric materials and how these should be employed in a neutron or x-ray experiment, and Paul Thompson (ESRF) who gave an overview of the measurement capabilities at the XMaS beamline, which is ideally suited to the study of multiferroics. Finally, the afternoon session finished with an open discussion chaired by Bob Cernik (University of Manchester). 

The group ascertained that the main experimental interests in this field focus on the ability to perform in-situ magnetoelectric and piezoelectric measurements. This workshop was a first milestone for the development of fundamental research in the field of multiferroics and x-ray/neutron scattering. 

View the presentations from the workshop