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An efficient application of a material is only possible if we know its physical and chemical properties, which is frequently obstructed by the presence of micro‐ or macroscopic inclusions of secondary phases. While sometimes a sophisticated synthesis route can address this issue, often obtaining pure material is not possible. One example is TaGeIr, which has highly sample‐dependent properties resulting from the presence of several impurity phases, which influence electronic transport in the material. The effect of these minority phases was avoided by manufacturing, with the help of focused‐ion‐beam, a μm‐scale device containing only one phase—TaGeIr. This work provides evidence for intrinsic semiconducting behavior of TaGeIr and serves as an example of selective single‐domain device manufacturing. This approach gives a unique access to the properties of compounds that cannot be synthesized in single‐phase form, sparing costly and time‐consuming synthesis efforts. 

In standard doping, adding charge carrier to a compound results in a shift of the Fermi level towards the conduction band for electron doping and towards the valence band for hole doping. We discuss the curious case of antidoping, where the direction of band movements in response to doping is reversed. Specifically, p-type antidoping moves the previously occupied bands to the principal conduction band resulting in an increase of band gap energy and reduction of electronic conductivity. We find that this is a generic behavior for a class of materials: early transition and rare earth metal (e.g., Ti, Ce) oxides where the sum of composition-weighed formal oxidation states is positive; such compounds tend to form the well-known electron-trapped intermediate bands localized on the reduced cation orbitals. What is less known is that doping by a hole annihilates a single trapped electron on a cation. The latter thus becomes electronically inequivalent with respect to the normal cation in the undoped lattice, thus representing a symmetry-breaking effect. We give specific theoretical predictions for target compounds where hole antidoping might be observed experimentally: Magnéli-like phases (i.e., CeO2-x and TiO2-x) and ternary compounds (i.e., Ba2Ti6O13 and Ba4Ti12O27), and note that this unique behavior opens the possibility of unconventional control of materials conductivity by doping.