Researchers at the Department of Energy in the US think they might have a new insight into how superconductivity breaks down as temperature rises. They hope the discovery could one day lead to superconductivity at – wait for it – room temperature.
Writing in Nature, the team says it observed a change in electron behaviour as a doped copper-oxide superconductor passed through a range of temperatures known as the 'pseudogap phase'. This is the point at which superconductivity breaks down, so if there is an answer to be found as to why room temperature superconductivity is not possible yet, it could well be found in the pseudogap.
The researchers looked at how electrons moved from oxygen site to oxygen site as the current flowed and discovered that things were not the same at each oxygen site within each copper-oxide unit.
Team leader Seamus Davis writes: “Picture the copper atom at the center [sic] of the unit, with one oxygen to the 'north' and one to the 'east,' and this whole unit repeating itself over and over across the copper-oxide layer. In every single copper-oxide unit, the tunneling [sic] ability of electrons from the northern oxygen atom was different from that of the eastern oxygen.”
Next the team says it wants to investigate exactly how this directional asymmetry affects the ability of electrons to move through the whole system, and to find other copper-oxide superconductors with similar so-called broken symmetries.
If the team can work out a route to room temperature superconductivity, the benefits would be huge. In theory, moving current through the electrical grid with no energy loss should save huge amounts of energy. In practice, the vast quantities of coolants needed to get the superconductors to work means there is no net gain. Eliminating the coolants would, as Davis says “save enormous amounts of money and [update] the electrical grid to meet the needs of the 21st Century.”