Observation of Magnetic Feshbach Resonances in Li-Yb Mixtures

We observe multiple interspecies magnetic Feshbach resonances between the open-shell Li and the closed-shell Yb ground state atom [1]. We resolve closely-located resonances that arise from a weak separation-dependent hyperfine coupling between the nuclear spin of ${}^{173}$Yb and the electronic spin of ${}^6$Li, and confirm their magnetic field spacing by ab initio electronic-structure calculations. Resonances are identified via trap-loss spectroscopy with the mixtures in a crossed optical dipole trap and varying magnetic field. The asymmetric loss profiles of the resonances show that three-body recombination in fermionic mixtures has a p-wave Wigner threshold. We plan to apply these resonances towards magnetoassociation of ultracold YbLi molecules in the electronic ground state. The ${}^2 \Sigma$ YbLi molecule possesses both electric and magnetic dipole moments that can be utilized towards ultracold chemistry, quantum many-body physics, and quantum information. [1] A. Green et al. arXiv: 1912.04874 (2019)