Hannover 2013 – scientific programme
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A: Fachverband Atomphysik
A 6: Ultra-cold atoms, ions and BEC II (with Q)
A 6.6: Talk
Monday, March 18, 2013, 15:15–15:30, F 428
Attractive atom-dimer interaction on the repulsive side of a 6Li-40K Feshbach resonance — •Michael Jag1,2, Matteo Zaccanti1, Marko Cetina1, Rianne Lous1, Dmitri Petrov3, Jesper Levinsen4, Florian Schreck1, and Rudolf Grimm1,2 — 1IQOQI, Österreichische Akademie der Wissenschaften, Innsbruck, Austria — 2Inst. für Experimentalphysik, Universität Innsbruck, Innsbruck, Austria — 3LPTMS, CNRS, Université Paris Sud, Orsay, France — 4Cavendish Laboratory, Cambridge, UK
Mass imbalance in strongly interacting mixtures of ultracold fermions is predicted to lead to new pairing phenomena and quantum phases. We investigate a mass-imbalanced 6Li-40K Fermi-Fermi mixture in the regime of strong interactions on the repulsive side of an interspecies Feshbach resonance. We find that, for a sufficiently strong repulsive s-wave interaction, the 40K atoms and the 6Li40K dimers interact attractively, which is in strong contrast to the mass-balanced case. This surprising behavior is related to the existence of a ↑ ↑ ↓ trimer state in ↑ ↓ Fermi-Fermi mixtures with a mass ratio m↑/m↓>8.2. For lower mass ratios (i.e. mK/mLi=6.64) this trimer state turns into a p-wave atom-dimer scattering resonance. Here, we present our experimental results on interactions in a resonantly interacting atom-dimer mixture. Employing radio-frequency spectroscopy over a range of temperatures and interaction strengths, we confirm the presence of a strong attraction on the repulsive side of a Feshbach resonance, in good agreement with theory.