Observation of a strong atom-dimer attraction in a mass-imbalanced fermi-fermi mixture

Michael Jag, Matteo Zaccanti, Marko Cetina, Rianne S Lous, Florian Schreck, Rudolf Grimm, Dmitry S Petrov, Jesper Fredenslund Levinsen

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We investigate a mixture of ultracold fermionic 40K atoms and weakly bound 6Li40K dimers on the repulsive side of a heteronuclear atomic Feshbach resonance. By radio-frequency spectroscopy we demonstrate that the normally repulsive atom-dimer interaction is turned into a strong attraction. The phenomenon can be understood as a three-body effect in which two heavy 40K fermions exchange the light 6Li atom, leading to attraction in odd partial-wave channels (mainly p wave). Our observations show that mass imbalance in a fermionic system can profoundly change the character of interactions as compared to the well-established mass-balanced case.
Original languageEnglish
Article number075302
Number of pages5
JournalPhysical Review Letters
Issue number7
Publication statusPublished - 2014
Externally publishedYes


  • Gases
  • Superfluid phase
  • Fermions

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