LMU chemists have synthesized a ferromagnetic superconducting compound that is amenable to chemical modification, opening the route to detailed studies of this rare combination of physical properties.
Superconductivity and ferromagnetism – the “normal” form of magnetism, such as that found in the familiar horseshoe magnet – are like chalk and cheese: They generally don’t go together. Ferromagnets are magnetic because the parallel alignment of adjacent electron spins in the iron atoms generates a strong internal magnetic field.
The new compound is made up of stacks of alternating superconducting iron selenide and ferromagnetic lithium-iron hydroxide layers. (Source: Dirk Johrendt)
Almost all known superconductors, on the other hand, form pairs of “anti-aligned” electrons and exclude magnetic field lines from their interiors. But LMU chemists have discovered a new material in which these two properties can coexist:
“We have synthesized a new compound which exhibits both characteristics at the same time: It is a ferromagnetic superconductor,” says Professor Dirk Johrendt of the Department of Chemistry. “This is an important advance, which opens up new research opportunities in the field,” he adds.
Ferromagnetic superconductors are not unknown, but they are exceedingly rare, and almost always exhibit both properties simultaneously only when they are cooled to temperatures close to absolute zero (-273°C). “The layered material which we have synthesized, (Li,Fe)OH(FeSe), has the great advantage that it works at higher temperatures, which are easier to achieve and handle in the laboratory,” says Johrendt.
The new compound is made up of stacks of alternating superconducting iron selenide (FeSe) and ferromagnetic lithium-iron hydroxide (Li,Fe)OH layers. When the material is cooled, electrical resistivity drops to zero in the iron selenide layer at temperatures below -230°C, and superconductivity emerges.
At somewhat lower temperatures, the iron atoms in the (Li,Fe)OH layer become ferromagnetic, but superconductivity persists nevertheless.
In cooperation with physicists from the Technical University in Dresden and the Paul Scherrer Institute in Villingen (Switzerland), the LMU researchers have demonstrated that the magnetic field generated by the (Li,Fe)OH layers penetrates into the interleaved superconducting layers – spontaneously and in the absence of externally applied fields.
This novel state of matter is referred to as a spontaneous vortex phase. The few substances which exhibit this effect cannot easily be chemically modified and require ultracold temperatures, making more detailed investigation very difficult.
“Our new compound for the first time gives us the chance to explore the influence of chemical modification on the coexistence of superconductivity and ferromagnetism, so that it should soon be possible to carry out more extensive studies of this fascinating phenomenon,” Johrendt concludes. (Angewandte Chemie 2014) göd
Luise Dirscherl | Eurek Alert!
New risk factors for anxiety disorders
24.02.2017 | Julius-Maximilians-Universität Würzburg
Stingless bees have their nests protected by soldiers
24.02.2017 | Johannes Gutenberg-Universität Mainz
In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
24.02.2017 | Life Sciences
24.02.2017 | Life Sciences
24.02.2017 | Trade Fair News