Nature volume 613, pages 463–467 (2023)
Conventional superconductivity emerges from pairing of charge carriers – electrons or holes – mediated by phonons. In many unconventional superconductors, the pairing mechanism is conjectured to be mediated by magnetic correlations, as captured by models of mobile charges in doped antiferromagnets. However, a precise understanding of the underlying mechanism in real materials is still lacking and has been driving experimental and theoretical research for the past 40 years. Early theoretical studies predicted magnetic-mediated pairing of dopants in ladder systems, where idealised theoretical toy models elucidated how pairing can emerge despite repulsive interactions. Here we experimentally observe this long-standing theoretical prediction, reporting hole pairing due to magnetic correlations in a quantum gas of ultracold atoms. By engineering doped antiferromagnetic ladders with mixed-dimensional couplings, we suppress Pauli blocking of holes at short length scales. This results in a drastic increase in binding energy and decrease in pair size, enabling us to observe pairs of holes predominantly occupying the same rung of the ladder. We find a hole-hole binding energy on the order of the superexchange energy, and, upon increased doping, we observe spatial structures in the pair distribution, indicating repulsion between bound hole pairs. By engineering a configuration in which binding is strongly enhanced, we delineate a strategy to increase the critical temperature for superconductivity.
To learn more about our recent publication please visit Nature.
Originally published 19 January 2023. Historical announcements retain their original dates and wording; positions and event invitations in older posts may have closed.
