Escalating Ferromagnetic Order via Se‐Vacancies Near Vanadium in WSe2 Monolayers

Magnetic order has been proposed to arise from a variety of defects, including vacancies, antisites, and grain boundaries, which are relevant in numerous electronics and spintronics applications. Nevertheless, its magnetism remains controversial due to the lack of structural analysis. The escalation of ferromagnetism in vanadium‐doped WSe2 monolayer is herein demonstrated by tailoring complex configurations of Se vacancies (SeVac) via post heat‐treatment. Structural analysis of atomic defects is systematically performed using transmission electron microscopy (TEM), enabled by the monolayer nature. Temperature‐dependent magnetoresistance hysteresis ensures enhanced magnetic order after high‐temperature heat‐treatment, consistent with magnetic domain analysis from magnetic force microscopy (MFM). The vanadium–Se vacancy pairing is a key to promoting ferromagnetism via spin‐flip by electron transfer, predicted from density‐functional‐theory (DFT) calculations. The approach toward nanodefect engineering paves a way to overcome weak magnetic order in diluted magnetic semiconductors (DMSs) for renovating semiconductor spintronics. The enhancement of ferromagnetism is demonstrated via Se‐vacancy engineering in V‐doped WSe2 diluted magnetic semiconductors and the underlying mechanism is elucidated. After generation of abundant Se‐vacancies via heat‐treatment, butterfly‐shaped hysteresis in the magnetoresistance curves and distinct magnetic domains are clearly observed. With state‐of‐the‐art atomic elemental mapping and comprehensive theoretical explanation, the origin of the enhanced ferromagnetism is revealed.