In this work, we find that Majorana fermions induce selective equal spin Andreev reflections (SESARs), in which incoming electrons with certain spin polarization in the lead are reflected as counter-propagating holes with the same spin. The spin polarization direction of the electrons of this Andreev reflected channel is selected by the Majorana fermions. Moreover, electrons with opposite spin polarization are always reflected as electrons with unchanged spin. As a result, the charge current in the lead is spin-polarized. Therefore, a topological superconductor which supports Majorana fermions can be used as a novel device to create fully spin-polarized currents in paramagnetic leads. We point out that SESARs can also be used to detect Majorana fermions in topological superconductors. [18,19]. Introduction-In this work, we point out another intriguing phenomenon due to the self-Hermitian property of MFs, namely, MF-induced selective equal spin Andreev reflections (SESARs). As depicted in Fig.1, when a spinful paramagnetic normal lead is coupled to a topological superconductor through its MF end state, electrons with spin pointing to a certain direction n are reflected as holes with the same spin (Fig.1a), where n is determined by the properties of the topological superconductor. The reflected holes are created due to missing electrons with spin polarization n below the Fermi energy. Therefore, these processes are called equal spin Andreev reflections. This is in sharp contrast to ordinary Andreev reflection processes [20], in which the reflected holes are created due to missing electrons below the Fermi energy which have opposite spins to the incoming electrons.Even more interestingly, at the normal lead/topological superconductor (N/TS) junction, electrons with opposite spin polarization − n are completely decoupled from the MF and they cannot participate in Andreev reflections (Fig.1b). In other words, the MF selects electrons with certain spin polarization n to undergo equal spin Andreev reflections. Therefore, we refer to this new phenomenon as MF-induced SESARs.Pure equal spin Andreev reflections can take place at a half-metal/superconductor interface [21-28] if spin is not conserved at the interface. This is because conducting electrons in a half-metal are fully spin-polarized and usual Andreev reflection processes cannot occur. Nevertheless, as we show below, inducing SESARs in paramagnetic leads is a special property of MFs. Importantly, as in the half-metal case and depicted in Fig.1a, the charge

A chain of iron atoms on lead may reveal a signature of the elusive Majorana particle [Also see Research Article by Nadj-Perge et al. ]