Observation of low-field Feshbach resonances between 161Dy and 40K

We report on the observation of Feshbach resonances at low magnetic-field strength (below 10 G) in the Fermi-Fermi mixture of 161Dy and 40K. We characterize five resonances by measurements of interspecies thermalization rates and molecular binding energies. As a case of particular interest for future experiments, we consider a resonance at 7.29 G, which combines accurate magnetic tunability and access to the universal regime of interactions with experimental simplicity. We show that lifetimes of a few hundred milliseconds can be achieved for the optically trapped, resonantly interacting mixture. We also demonstrate the hydrodynamic expansion of the mixture in the strongly interacting regime and the formation of DyK Feshbach molecules. Our work opens up experimental possibilities in view of mass-imbalanced superfluids and related phenomena.

Automated summary

In this work, we report the observation of Feshbach resonances at low magnetic-field strength in the Fermi-Fermi mixture of 161Dy and 40K. We characterized five resonances by measuring interspecies thermalization rates and molecular binding energies. One resonance at 7.29 G, which offers both accurate magnetic tunability and access to the universal regime, is highlighted as particularly interesting for future experiments. We demonstrate that optically trapped, resonantly interacting mixture can achieve lifetimes of a few hundred milliseconds. Additionally, we show the hydrodynamic expansion of the mixture in the strongly interacting regime and the formation of DyK Feshbach molecules. Our work opens up experimental possibilities for mass-imbalanced superfluids and related phenomena.