Researchers at the University of Valencia show that the superconducting state can be maintained even when the material in question is reduced from three to two dimensions, making the efficiency gains needed for technologies like those underlying the frictionless train possible.
An international research team led by Eugenio Coronado, of the Univeristy of Valencia’s Institute of Molecular Science (ICMol) has shown that it is possible to maintain superconductivity at the two-dimensional limit, currently one of the most hotly debated issues in solid state physics. This finding allows us to advance our understanding of superconductivity and paves the way for the miniaturisation of ultrasensitive magnetic field detectors. The work was published in Nature Communications.
Superconductivity is one of the most fascinating quantum phenomena in physics. In the superconducting state, materials conduct electricity without energy loss, which makes them very efficient for many applications including the manufacture of the strongest known magnets, ultrasensitive magnetic field detectors, efficient energy conduction and frictionless transportation (levitating trains).
Since its discovery in 1911, one of the issues that has most intrigued scientists is whether it is possible to maintain the superconducting state even when the material is reduced from three to two dimensions. Intuitively we expect that it would be more difficult to stabilise the superconducting state when the dimensionality is reduced. With the isolation of graphene, the first two-dimensional material, made up of a single layer of carbon atoms, the issue been pushed resolutely to the fore. However, despite graphene’s extraordinary mechanical, electrical and magnetic properties, superconductivity has so far remained an elusive property.
Based at the UV’s Science Park, ICMol researchers have shown that superconductivity can indeed be maintained at this two-dimensional limit. The researchers have studied layered materials similar to graphene, but which become superconductors when cooled to low temperatures. Specifically, they have studied the electrical properties of a large family of layered materals known as metal dichalcogenides.
A research team led by the U.S. Department of Energy’s (DOE’s) Argonne National Laboratory has discovered that only half the atoms in some iron-based superconductors are magnetic, providing a conclusive demonstration of the wave-like properties of metallic magnetism in these materials.
The discovery allows for a clearer understanding of the magnetism in some compounds of iron, the iron arsenides, and how it helps induce superconductivity, the resistance-free flow of electrical current through a solid-state material, which occurs at temperatures up to 138 degrees Kelvin, or minus -135 degrees Celsius.
“In order to be able to design novel superconducting materials, one must understand what causes superconductivity,” said Argonne senior physicist Raymond Osborn, one of the project’s lead researchers. “Understanding the origin of magnetism is a first vital step toward obtaining an understanding of what makes these materials superconducting. Given the similarity to other materials, such as the copper-based superconductors, our goal was to improve our understanding of high-temperature superconductivity.”
Understanding the origin of magnetism is a first vital step toward obtaining an understanding of what makes these materials superconducting.
From an applied perspective, such an understanding would allow for the development of magnetic energy-storage systems, fast-charging batteries for electric cars and a highly efficient electrical grid, said Argonne senior physicist Stephan Rosenkranz, the project’s other lead researcher.
Superconductors reduce power loss. The use of high-temperature superconducting materials in the electrical grid, for example, would significantly reduce the large amount of electricity that is lost as it travels though the grid, enabling the grid to operate more efficiently.
The researchers were able to show that the magnetism in these materials was produced by mobile electrons that are not bound to a particular iron atom, producing waves of magnetization throughout the sample. They discovered that, in some iron arsenides, two waves interfere to cancel out, producing zero magnetization in some atoms. This quantum interference, which has never been seen before, was revealed by Mössbauer spectroscopy, which is extremely sensitive to the magnetism on each iron site.
Superconductivity could have implications for creating technologies like ultra-efficient power grids and magnetically levitating vehicles
Physicists at the have led an international team that has come closer to understanding the mystery of how superconductivity, an exotic state that allows electricity to be conducted with practically zero resistance, occurs in certain materials.
Physicists all over the world are on a quest to understand the secrets of superconductivity because of the exciting technological possibilities that could be realized if they could make it happen at closer to room temperatures. In conventional superconductivity, materials that are cooled to nearly absolute zero ( ?273.15 Celsius) exhibit the fantastic property of electrons pairing up and being able to conduct electricity with practically zero resistance. If superconductivity worked at higher temperatures, it could have implications for creating technologies such as ultra-efficient power grids, supercomputers and magnetically levitating vehicles.
The new findings from an international collaboration, led by Waterloo physicists David Hawthorn, Canada Research Chair Michel Gingras, doctoral student Andrew Achkar and post-doctoral student Zhihao Hao,present direct experimental evidence of what is known as electronic nematicity – when electron clouds snap into an aligned and directional order – in a particular type of high-temperature superconductor. The results, published in the prestigious journal Science, may eventually lead to a theory explaining why superconductivity occurs at higher temperatures in certain materials.