In the quest for room-temperature superconductivity, an international team of physicists has uncovered a link between magnetism and the mysterious phase of matter known as the pseudogap, which may finally yield clues to achieving superconductivity above frigid, artificial temperatures.
Given the artificially cold temperatures on which current superconducting technologies rely, making their use impractical for many applications, the search for new room-temperature superconducting materials is a major goal of applied physics research.
Now, physicists from the Max Planck Institute of Quantum Optics in Germany and the Center for Computational Quantum Physics (CCQ) at the Simons Foundation’s Flatiron Institute in New York City are potentially helping to advance scientists closer than ever to superconducting at practical temperatures, as reported in a recent paper published in the Proceedings of the National Academy of Sciences.
Superconductors
Superconductors are materials that allow electrical current to flow without resistance. However, even in superconducting materials, the property only becomes active below a threshold temperature. This limits technological applications, as the materials require bulky cooling apparatus to maintain the desired temperatures, which are well below typical room temperatures.
Despite the volume of research involving superconductivity, in many ways it remains poorly understood, awaiting insights that will enable the next generation of quantum computing and other applications.
Some superconductors operate at what are considered “high temperatures,” although, in practical terms, these are still well below typical room temperatures and usually only slightly above absolute zero. What is interesting about those materials, however, is that they tend to exhibit a “pseudogap state” in which electrons begin to behave strangely as they transition to a superconducting state.
Understanding how this state leads to superconductivity could be essential to revealing the mechanisms at play and then applying them to produce room-temperature superconductors.
Testing the Pseudogap
Advancing toward resolving this long-standing issue, researchers used a quantum simulator set slightly above absolute zero to monitor electron spins. They identified that the up or down spins of electrons were influenced by their neighbors in a universal pattern.
At the center of the team’s work was the Fermi-Hubbard model, which describes electron interactions in a solid. The research team’s simulations successfully recreated this model, rather than a real-world material, using lithium atoms in an optical lattice of laser light at temperatures on the order of billionths of a degree above absolute zero. Simulations allowed the researchers a level of precision control impossible in real-world experiments.
When materials host an unaltered amount of electrons, they spin in an alternating pattern called antiferromagnetism. Through a process called “doping,” electrons can be removed, disrupting the magnetic order in a way that physicists had long assumed was permanent. Yet in the new observations, the team discovered a hidden layer of organization present beneath the seeming chaos at very low temperatures.
Hellbound and Down 