Mn substitution induced a ferrimagnetic to ferromagnetic transition in trigonal $\text{Cr}_5\text{Te}_8$

Tailoring the magnetic properties of chromium tellurides via heterointercalation with extrinsic transition metals remains largely unexplored. Here, we report a comprehensive investigation of trigonal Cr$_5$Te$_8$ and Cr$_4$MnTe$_8$ single crystals, in which Mn substitution elevates the magnetic ordering temperature from 226 to 249 K and enhances the saturation magnetic moment per magnetic ion ($m_{\text{S}}$) from 2.00 to 2.66 $\mu_{\text{B}}$ at 5 K. Remarkably, the observed $m_{\text{S}}$ enhancement significantly exceeds the contribution of Mn ion moments alone, indicating the relief of intrinsic spin compensation within the parent lattice. First-principles calculations definitively establish that pristine $\text{Cr}_5\text{Te}_8$ exhibits ferrimagnetic ordering with a computed $m_\text{S}$ of 1.98~$\mu_\text{B}$, and further reveal that preferential occupation of the van der Waals gaps by Mn ions induces a ferrimagnetic-to-ferromagnetic transition, yielding a predicted $m_\text{S}$ of 2.94~$\mu_\text{B}$. These findings not only resolve the magnetic ground state of trigonal Cr$_5$Te$_8$ but also identify heterointercalation as a robust strategy for engineering the spin textures of chromium tellurides.