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Magnetic semiconducting materials offer tremendous prospects for spin electronics but is challenging to achieve room-temperature ferromagnetism with unambiguous origin. Herein, a non-stoichiometry strategy is proposed to induce tunable magnetization in MoSe2−x nanoflowers via vacancy-controlled 2H–1T phase transition. The resultant MoSe2−x exhibits robust room-temperature ferromagnetism with significant positive correlation to the content of 1T phase and 2H–1T interfaces. Significant magnetic hysteresis and Curie transition above room temperature have been achieved, confirming the ferromagnetic feature of MoSe2−x. To examine the origin of ferromagnetism, formation energy and spin-polarized calculations have been conducted, indicating that the Se vacancy is beneficial for the formation of the 1T phase and interfacial spin polarization. Localized magnetic moments induced at the 2H–1T interfaces exhibit enhanced magnetism as compared to the net moments from the 1T orbital splitting, giving rise to strong coupling bound magnetic polarons. This work not only advances the understanding on the origin of magnetism in magnetic semiconductors, but also provides an effective route to generate ferromagnetism by defect and/or interface engineering that could be applied to multiferroics, spintronics, and valleytronics. [ABSTRACT FROM AUTHOR]

Amorphous MoSe2 has been fabricated hydrothermally, and the degree of amorphousness was tuned by post-annealing procedures. Large room temperature ferromagnetism (RTFM) has been achieved for the amorphous MoSe2 which weakens during crystallization and phase transition from the 1T to the 2H structure. Theoretical calculations indicate that the amorphous MoSe2 exhibits higher magnetization compared with the crystalline 1T and 2H phases and that the magnetization mainly originates from the d orbitals of Mo atoms. This study provides insights into the RTFM for the amorphous transition metal dichalcogenides (TMDs) and provides amorphousness as a new option to tailor the magnetization of the TMDs for future spintronic applications. [ABSTRACT FROM AUTHOR]