Observation of Feshbach resonances in an ${}^{167}$Er-${}^6$Li Fermi-Fermi mixture

We present our experimental investigation of the interspecies Feshbach spectrum in a mixture of ${}^{167}$Er($F=19\mathrm{/}2,m_F=-19\mathrm{/}2$)-${}^6$Li($F=1\mathrm{/}2,m_F=1\mathrm{/}2$) atoms in the microkelvin temperature regime. These temperatures are achieved by means of sympathetic cooling with ${}^{174}$Yb as a third species. Interspecies Feshbach resonances are then identified by investigation of the Er-Li inelastic collisional properties for magnetic fields up to 800 G. Numerous narrow resonances as well as six resonances with widths above 1 G could be identified. It is these broader resonances that hold much promise for interesting future investigations of, for exmample, novel superfluid states and Efimov states in large mass-imbalanced, all-fermionic two-component systems.