A team of researchers from three countries synthesized a material that exhibits superconducting properties and is capable of creating a magnetic field. It was possible due to the symmetry violation of time reversal. Article about the discovery is published in the journal Nature Physics.
Some physical systems are symmetric in time, and coordinates in the “inverse time” their properties can change. An example of such systems — superconductors in a special quantum state. Below a certain temperature they start conducting current without resistance and thus ideal diamagnetically — that is, displaced from the external magnetic field. Thanks to this feature, the magnet is able to “fly” above the superconductor.
Thus, the magnetism and the superconductivity, in fact, been considered mutually exclusive properties. Magnetism occurs in the structure due to the presence in the material of atoms with unpaired electrons. But for the occurrence of superconductivity the electrons are paired, forming Cooper pairs, which, without energy losses move through the crystal lattice. The magnetic centers of the prevent the formation of electron pairs, so split the electrons are “on duty” is not possible. Simultaneously, these two properties can only occur in the atomic structures, the spontaneous appeal of symmetry in time.
Researchers from the technical University of Dresden, Institute of solid state physics and materials research Leibniz Association, National Institute of advanced industrial science and technology (Tokyo, Japan) and chemical faculty of Moscow state University have created and investigated a structure of superconductors of the composition Ba1-xKxFe2As2 with broken symmetry relative to time reversal. The researchers found that when x about 0.7 and a temperature of 10 Kelvin (-263 °C) the material there is a symmetry breaking. In this state, the connection creates a magnetic field simultaneously with superconductivity.
The authors have studied the connection of this composition with various x, which are synthesized and their single crystals as thin plates with dimensions up to one, see the researchers Then analyzed how the material will interact with the beam of muons. To change the magnetic moment of the particle beam, the scientists determined the magnetic structure of the crystal. “The results indicate that a number of superconductors under certain compositions shows the little-known form of magnetism. What is surprising is that this magnetism is generated by superconductivity, and that makes this phenomenon particularly interesting. Further study of this phenomenon opens new opportunities for creation of superconducting devices,” explained one of the key research participants, erase��nick at the Technical University of Dresden Vadim Grinenko.
