Theoretical investigation of the magnetic semiconductor nature in PbI₂ monolayer induced by Fe doping

Transition metal doping in two-dimensional (2D) semiconductor materials is an efficient way to develop new spintronic materials. In this work, the effects of Fe doping on the PbI₂ monolayer electronic and magnetic properties are investigated using first-principles calculations. The pristine PbI₂ monolayer is an indirect-gap semiconductor with a band gap of 2.50 eV. Fe doping induces effective magnetism engineering in this 2D material with a total magnetic moment of 4.00 µ _B and in-plane magnetic anisotropy (IMA). Herein, the magnetism is produced mainly by Fe impurities. Parallel spin coupling with perpendicular magnetic anisotropy (PMA) is found in the monolayer doped with two Fe atoms (2Fe@PbI₂), meanwhile the triangular doping configuration (3Fe@PbI₂) induces antiparallel spin coupling with the IMA. Codoping with Br atoms can enhance the thermodynamic stability and tune the system magnetism. Specifically, Br codoping induces the ferromagnetic-to-antiferromagnetic state transition in the 2Fe@PbI₂ system and enhances the antiparallel spin coupling in the 3Fe@PbI₂ system. Moreover, the PMA and IMA in these systems, respectively, are also affected, becoming weaker. In all cases of doping and codoping, the magnetic semiconductor nature with relatively large spin-dependent energy gaps is obtained. Our findings introduce the doped and codoped PbI₂ monolayer systems as new promising 2D spintronic materials with a magnetic semiconductor nature and tunable magnetic anisotropy, which can be selectively employed for magnetic field sensing and Magnetoresistive Random Access Memories (MRAMs) fabrication.