We present a detailed study of the scattering properties of ultracold mixtures of bosonic potassium atoms. We locate 20 previously unobserved Feshbach resonances in isotopic ${}^{39}\mathrm{K}\text{−}{}^{41}\mathrm{K}$ mixtures. These are assigned to $s$-wave molecular channels by comparison to an asymptotic bound state model and coupled-channel calculations. Additional Feshbach resonances are studied in spin mixtures of a single potassium isotope, both in ${}^{39}\mathrm{K}$ and ${}^{41}\mathrm{K}$. In particular, we characterize the parameters of a selected ${}^{39}\mathrm{K}$ Feshbach resonance by radio-frequency association of Feshbach molecules. Our results could be exploited to refine the model potentials for potassium scattering. Furthermore, these new Feshbach resonances enlarge the range of experiments possible with degenerate Bose-Bose mixtures.

• Received 29 October 2018

DOI:https://doi.org/10.1103/PhysRevA.98.062712