Jong Soo Lim, Llorens Serra, Rosa Lopez, Ramon Aguado
We study the emergence of Majorana bound states (MBS) in multiband
semiconductor wires with Rashba spin-orbit (SO) coupling, proximity coupled to
an s-wave superconductor and in the presence of an external magnetic field. We
consider long, but \emph{finite}, multiband wires (namely, quasi-1D wires with
dimensions $L_x\gg L_y$). Our numerically exact results demonstrate that
interband mixing coming from Rashba SO (Rashba mixing) hybridizes Majorana
pairs originating from different transversal modes while simultaneously closing
the effective gap. Thus, regions were many MBS coexist are effectively trivial
owing to Rashba mixing. On the contrary, Majorana physics is robust provided
that only one single transversal mode, not necessarily the lowest one,
contributes with a Majorana pair. We also find that Majorana physics is fragile
with respect to orbital effects induced by any small out-of-plane component of
the magnetic field.
View original:
http://arxiv.org/abs/1202.5057
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