Spin-orbit coupling facilitates the exploitation of spin degrees of freedom of an electron in the absence of any external magnetic field, opening up new possibilities for spintronics-based applications. In this work, we have conducted a detailed investigation of spin-orbit coupling-induced novel physical effects in noncentrosymmetric ${\mathrm{Ta}}_2{\mathrm{CS}}_2$, a representative member of the MXene family. We find that local symmetries and orbital compositions are responsible for the nontrivial band splitting and characteristic spin textures displayed by these systems at various high-symmetry points in the Brillouin zone. First-principles calculations, supplemented by a $\mathbf{k}·\mathbf{p}$ model Hamiltonian, demonstrate the presence of both linear and higher-order Rashba terms at the Brillouin zone (BZ) center $\mathrm{\Gamma }$, where the system exhibits little-group symmetry $C_{3v}$. Additionally, we observe valley-dependent Zeeman-type spin splitting at the non-time-reversal invariant momentum (TRIM) points $K$ and $K^{\prime }$. Furthermore, we identify that the opposite spin splitting at the $K$ and $K^{\prime }$ points arises from a complex orbital composition that induces an intrinsic orbital moment, influencing the nature of spin splitting. Our findings indicate that ${\mathrm{Ta}}_2{\mathrm{CS}}_2$ shares many key physical properties with transition metal dichalcogenides (TMDCs), making it a promising candidate for spintronic and valleytronic applications.

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• 2-dimensional systems
• MAX phase compounds
• Band structure methods
• Density functional theory
• Electronic structure
• k dot p method