ABSTRACT: We present a joint experimental and theoreticalstudy on double iron atom doped germanium clusters, Fe2Gen−/0 (n= 3−12). The experimental photoelectron spectra of cluster anionsare reasonably reproduced by theoretical simulations. The low-lyingstructures of the iron-doped semiconductor clusters are obtained byusing an ab initio computation-based genetic-algorithm globaloptimization method. We find that the smaller-sized Fe2Gen− (n =3−8) clusters adopt bipyramid-based geometries, while the largerones (n ≥ 9) adopt polyhedral cagelike structures with one interiorFe atom. Interestingly, starting from n = 8, the most stable anionicclusters Fe2Gen− exhibit structures that are different from that oftheir neutral counterparts Fe2Gen. Robust ferromagnetic interactionis found between the two doped iron atoms in the neutral clustersFe2Gen, while the total spin moment always remains at 4 μB for all the neutral double iron atom doped germanium clusters up ton = 12. This behavior is in stark contrast to the magnetic quenching behavior typically observed in germanium clusters dopedwith a single Fe atom