Renormalization of the Majorana bound state decay length in a perpendicular magnetic field.

Orbital effects of a magnetic field in a proximitized semiconductor nanowire are studied in the context of the spatial extent of Majorana bound states. We develop an analytical model that explains the impact of concurring effects of paramagnetic coupling of the nanowire bands via the kinetic energy operator and spin-orbit interaction on the Majorana modes. We find that the perpendicular field, so far considered to be detrimental to the Majorana fermion formation, is, in fact, helpful in establishing the topological zero-energy modes in a finite system due to significant decrease in the Majorana decay length. [ABSTRACT FROM AUTHOR]