  Recent works have predicted materials featuring bands with a large
spin-splitting distinct from ferromagnetic and relativistically spin-orbit
coupled systems. Materials displaying this property are known as altermagnets
and feature a spin-polarized band structure reminiscent of a $d$-wave
superconducting order parameter. We here consider the contact between an
altermagnet and a superconductor and determine how the altermagnetism affects
the fundamental process of Andreev reflection. We show that the resulting
charge conductance depends strongly on the interfacial orientation of the
altermagnet relative to the superconductor, displaying features similar to
normal metals or ferromagnets. The zero-bias conductance peak present at the
interface in the $d$-wave case are robust toward the presence of an
altermagnetic interaction. Moreover, the spin conductance strongly depends on
the orientation of the altermagnet relative the interface. These results show
how the anisotropic altermagnetic state can be probed by conductance
spectroscopy and how it offers voltage control over charge and spin currents
that are modulated due to superconductivity.
