In the paper published by the scientists in Physical Review B: Condensed Matter And Materials Physics, they discuss so-called pseudogapped superconductors.
Physicists Mikhail Feigel'man (the head of MIPT's theoretical nanophysics laboratory) and Lev Ioffe have explained the unusual effect in a number of promising superconductor materials. Using a theory they developed previously, the scientists have linked superconducting carrier density with the quantum properties of a substance.
The term "gap" appears in the quantum theory of superconductivity and is a definition for the characteristic gap in an electron energy distribution diagram, the energy spectrum. A distinction is made between superconductors with a "conventional" gap and special superconductors, which, even in their normal state, demonstrate something similar to a gap – it is called a "pseudogap."
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