Evidence for the Existence of Magnon-Mediated Attraction in the Parent Cuprates

Magnon-mediated interactions are the effective interactions between two doped holes, arising from the exchange of a magnon. In the context of cuprates, this magnon-mediated interaction has long been believed to be attractive and, therefore, a main component of the "glue" leading to superconductivity. We develop a method to study these magnon-mediated interactions between two-holes injected into the otherwise undoped CuO2-layer, using a three-band model. The main challenge is to be able to distinguish processes where a magnon is exchanged between holes from those where the magnon is emitted and reabsorbed by the same hole. Our method allows us to isolate the effect of magnon-mediated interactions and to prove that they are indeed attractive in the parent cuprates.