  Spin-split superconductors exhibit an electron-hole asymmetric spin-resolved
density of states, but the symmetry is restored upon averaging over spin. On
the other hand, asymmetry appears again in tunneling junctions of spin-split
superconductors with a spin-polarized barrier. As demonstrated recently in both
theory and experiment, this fact leads to a particularly strong thermoelectric
effect in superconductor-ferromagnet structures. In this work we show another
important effect stemming from the electron-hole asymmetry - current
rectification. We calculate the charge current in spin-polarized tunnel
junctions of normal metal and a spin-split superconductor with AC and DC
voltage bias. In the DC case, the I-V curve is not fully antisymmetric and has
a voltage-symmetric component due to spin polarization. This translates to the
existence of a rectified current in the AC case, which is proportional to the
spin polarization of the junction and strongly depends on the frequency of the
applied bias. We discuss possible applications of the rectification effect,
including a diode for superconducting electronics and radiation detectors. The
analysis of the rectified charge current is supplemented by the discussion of
heat current and relevant noise correlators, where electron-hole asymmetry also
plays an important role, and which are useful for applications in detectors.
