Formation of ultracold fermionic NaLi Feshbach molecules

We describe the formation of fermionic NaLi Feshbach molecules from an ultracold mixture of bosonic ²³Na and fermionic ⁶Li. Precise magnetic field sweeps across a narrow Feshbach resonance at 745 G result in a molecule conversion fraction of $5%$ for our experimental densities and temperatures, corresponding to a molecule number of 5×10⁴. The observed molecular decay lifetime is $1.3$ ms after removing free Li and Na atoms from the trap. Due to its extremely low reactivity, NaLi molecules in the ground state will have a much longer lifetime than KRb.