  We adapt the block-Lanczos density-matrix renormalization-group technique to
study the spin transport in a spin chain coupled to two non-interacting
fermionic leads. As an example, we consider leads described by two-dimensional
tight-binding models on a square lattice. Although the simulations are carried
out using a chain representation of the leads, observables in the original
two-dimensional lattice can be calculated by reversing the block-Lanczos
transformation. This is demonstrated for leads with Rashba spin-orbit coupling.
