We investigate equilibrium (background), linear, and nonlinear spin currents in two-dimensional Rashba spin-orbit coupled altermagnet systems, using a modified spin current operator that includes anomalous velocity arising from nonzero Berry curvature. The background spin current, stemming from spin-orbit coupling and modulated by the altermagnet term ($t_j$), exhibits in-plane polarization, increases linearly with Fermi energy (${\epsilon }_F$), and is enhanced by both the altermagnet ($t_j$) and the Rashba parameter ($\lambda$). Linear spin current is always transverse with out-of-plane polarization and can be viewed as a spin Hall current, primarily driven by band velocity, with $t_j$ enabling a band-induced contribution [previously absent in simple Rashba systems ($t_j=0$)]. This highlights the altermagnet system as a promising source of spin Hall current generation. For linear spin Hall current, its band contribution's magnitude increases linearly with ${\epsilon }_F$, while the magnitude of the anomalous component saturates at higher ${\epsilon }_F$. Further, the magnitude of the spin Hall current is enhanced by $t_j$ but reduced by $\lambda$. Nonlinear spin currents feature both longitudinal and transverse components with in-plane polarization. Both the nonlinear longitudinal spin current from band velocity and the nonlinear transverse spin current from anomalous velocity initially decrease with ${\epsilon }_F$ before saturating at higher ${\epsilon }_F$. Importantly, $t_j$ reduces these currents while $\lambda$ enhances them. Meanwhile, the nonlinear transverse current from band velocity increases and then saturates with ${\epsilon }_F$, enhanced by $\lambda$ and showing nonmonotonic variation with $t_j$. These findings highlight the tunability of spin current behavior through Rashba and altermagnet parameters, offering insights for spintronic applications.

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• Rashba coupling
• Spin Hall effect
• Spin current
• Spin-orbit coupling
• Spintronics
• Transport phenomena
• Altermagnets
• Two-dimensional electron system
• Boltzmann theory