Surprising similarity between stripy black holes and high-temperature superconductors
We don’t understand how some materials become superconducting at relatively high temperatures. Leiden physicists have now found a surprising connection with auxiliary black holes. It enables us to use our knowledge of black holes on the mystery of high-temperature superconductivity. Publication in Nature Physics on July 23rd.
Superconductivity, discovered in Leiden in 1911, is used in many modern applications, such as MRI scanners and particle accelerators. These exploit the surprising phenomenon that electric currents flow without resistance at temperatures close to absolute zero. Unfortunately continuous cooling requires lots of energy, so physicists all over the world are looking for a way to make materials that superconduct at higher temperatures.
All relatively high-temperature superconductors that we know are based on so-called Mott insulators. These form when electrons are stuck in their crystal lattice nodes, exactly one per node. They turn into superconductors when we inject extra electrons. We don’t understand why this happens on a fundamental level. If we did, we might be able to design even higher-temperature superconductors, which are easier to keep sufficiently cool.
We do know from experiments that halfway before the superconductor is formed, the imparity between the number of electrons and the number of available nodes within the crystal lattice causes a stripy pattern, much like the moving Moiré patterns we see on TV when an old-fashioned computer screen is filmed. But why? This is a key question in understanding Mott insulators.
Physicists are looking for the answer in an unexpected direction: they hypothesize that the dodgy electrons in high-temperature superconductors behave in some ways similarly to auxiliary black holes. Leiden physicists Alexander Krikun, Koenraad Schalm and Jan Zaanen together with Tomas Andrade from the University of Barcelona have now found the same stripy pattern in a similar discrepancy between auxiliary ‘wavy’ black holes and a crystal lattice. This confirms the hypothesis and means that we can use our knowledge about black holes to better understand high-temperature superconductivity.
Tomas Andrade, Alexander Krikun , Koenraad Schalm & Jan Zaanen, 'Doping the holographic Mott insulator', Nature Physics