Room-temperature ferromagnetism in semimetallic Co-intercalated MoTe2

Abstract

Fe-intercalated TaS2 prepared via the chemical intercalation of iron into van der Waals (vdW) layered 2H-TaS2 crystals enables hard ferromagnetic behavior, making it attractive for spintronic applications. However, the Curie transition at room temperature and no gate controllability in metallic TaS2 are still unfavorable. Here, we demonstrate the feasibility of realizing a ferromagnetic semimetal through the wet chemical intercalation of cobalt into semiconducting 2H-MoTe2, thereby leveraging its polymorphism. Transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy reveal the insertion of pure Co atoms within the vdW gap following the intercalation process. Co-intercalated MoTe2 (Co-MoTe2) demonstrates a conductivity of 1.5 orders of magnitude higher than that of 2H-MoTe2. This significant increase in the conductance facilitates the direct investigation of ferromagnetism through magnetotransport measurements. Co-MoTe2 exhibits a positive magnetoresistance of approximately 4 %, with hysteresis observed even at room temperature. Furthermore, density functional theory calculations corroborate the enhancement of the magnetoresistance ratio and Curie temperature, which is attributed to the ferromagnetism induced by local magnetic moments resulting from the incorporation of cobalt. This study paves the way for enhanced practical applications in future spintronics by demonstrating the effectiveness of integrating foreign magnetic atoms into the vdW gap, thereby increasing the operational temperature.