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!
Nanotubes built from protein crystals: Breakthrough in biomolecular engineering
15.11.2018 | Tokyo Institute of Technology
Insect Antibiotic Provides New Way to Eliminate Bacteria
15.11.2018 | Universität Zürich
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure
Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...
Physicists at ETH Zurich demonstrate how errors that occur during the manipulation of quantum system can be monitored and corrected on the fly
The field of quantum computation has seen tremendous progress in recent years. Bit by bit, quantum devices start to challenge conventional computers, at least...
09.11.2018 | Event News
06.11.2018 | Event News
23.10.2018 | Event News
15.11.2018 | Earth Sciences
15.11.2018 | Physics and Astronomy
15.11.2018 | Physics and Astronomy