Opposites Repel: ESS Scientist Discovers New Magnetic Phenomenon
For the first time, a novel magnetic state has been discovered, where the most basic concept of magnetism - that opposites attract - does not hold true. The phenomenon has been discovered and described by an international team of scientists lead by ESS Director for Science Dimitri Argyriou. The discovery holds promise for tomorrow's memory and sensor technology, enabling devices from phones to cars. The finding was reported in Nature Materials.
Phones, cars, TVs and kitchen appliances - most of the tools we use have small computers inside, and they all require memory. Product development proceeds at breakneck pace, and the computers have to be ever smaller, smarter, more energy efficient. In pursuit of tomorrow's data-handling technology, researchers at the European Spallation Source have unearthed a novel magnetic phenomenon.
No one can say what the next big breakthrough in data-handling technology will be, but a class of materials called multiferroics are promising candidates. One such material is terbium ferrite, which can store information so that it can be written with electricity and read magnetically, at a low energy cost. This may revolutionise memory and sensor technology - but a lot of research is required before the concept can be used in applications.
An international research team lead by Dimitri Argyriou, Director for Science at ESS, Sweden, has used neutrons to probe the inner workings of terbium ferrite. They found that at an atomic scale, the atoms arrange themselves in a grid of microscopic domains, each of which behaves like a small bar magnet. These magnets do not line up in the same direction, as one might expect. Instead, adjacent domains have opposite magnetic directions, placing north next to north and south next to south. The scientists were also surprised by the overall domain structure: they are unexpectedly large (albeit on a microscopic scale) and display extremely sharp domain boundaries.
- I was expecting domains perhaps 30 times smaller than what we observed, says Dimitri Argyriou. And the domain boundaries are exceptionally sharp - I've never seen anything like it. The structure shouldn't be stable, and yet it is.
Pursuing this mystery, the team of professor Maxim Mostovoy, a theoretical physicist at Groningen University, the Netherlands, provided a surprising insight. The unusual structure observed - large domains with sharp domain walls and alternately arranged magnetic moments - is stabilized by a novel magnetic phenomenon. Surprisingly, the opposite poles of a domain repel each other. Rather than red attracting white and red repelling red as with bar magnets, in terbium ferrite, opposites repel.
– Our discovery has many implications, says Maxim Mostovoy. We think that this interplay between iron and terbium atoms can be used to make new, more versatile multiferroics that can cover the increasing demands of lean technology with low power consumption.
This discovery previews the discoveries that ESS, the European facility for research with neutrons under development in southern Sweden, will bring.
– Without neutrons, this discovery would have passed us by, says Dimitri Argyriou. We need more powerful neutron sources in order to probe deeper into such new states of matter. Once built, ESS will help us unearth new phenomena like this one, which remain hidden from us today. This is one example of the many new things a facility like ESS will help us discover, not only in magnetic materials, but in a broad range of fields of science and technology.
For more information, please contact:
Dimitri Argyriou, ESS Director for Science, E-mail , Tel. +46-(0)46-888 30 32
Marianne Ekdahl, Communications Officer - Press & Politics. E-mail , Tel. +46-(0)46-888 30 66
ESS IN SHORT:
The European Spallation Source – the next generation facility for materials research and life science
The European Spallation Source (ESS) will be a multi-disciplinary research laboratory based on the world’s most powerful neutron source. ESS can be likened to a large microscope, where neutrons are used instead of light to study materials – ranging from polymers and pharmaceuticals to membranes and molecules – to gain knowledge about their structure and function. ESS will be around 30 times better than existing facilities, opening up new possibilities for researchers in for example health, environment, climate, energy, transport sciences and cultural heritage.
ESS is an intergovernmental research infrastructure project, and it will be built in Lund in southern Scandinavia. Currently 17 European countries are Partners in the ESS project, and will take part in the construction, financing and operation of the ESS. Sweden and Denmark will co-host the ESS and cover 50 percent of the 1,4 B€ investment costs and 20 percent of the operating costs together with the Nordic and Baltic states.
The European Spallation Source ESS AB is a public limited company, today owned by the Swedish and the Danish states. ESS AB is currently working on finalizing the ESS technical design, planning the future research at ESS, preparing for construction, and planning the future international ESS organisation. This is done in collaboration with a large number of research institutes, universities and laboratories around the world. Construction is expected to start in 2013, the ﬁrst neutrons to be produced in 2019 and the facility to be fully operational around 2025.
ESS is expected to support a user community of at least 5000 European researchers and will have great strategic importance for the development of the European Research Area. Near by there will be complementary laboratories, such as the synchrotron MAX IV in Lund and XFEL and PETRAIII in Hamburg.