Magnetic field effects on spin texturing in a quantum wire with Rashba spin-orbit interaction

A quantum wire with strong Rashba spin-orbit interaction is known to exhibit spatial modulation of spin density along its width owing to coupling between subbands caused by the Rashba interaction. This is known as spin texturing. Here, we show that a transverse external magnetic field introduces additional complex features in spin texturing, some of which reflect the intricate details of the underlying energy dispersion relations of the spin-split subbands. One particularly intriguing feature is a 90 degrees phase shift between the spatial modulations of two orthogonal components of the spin density, which is observed at moderate field strengths and when only the lowest spin-split level is occupied by electrons. Its origin lies in the fact that the Rashba interaction acts as an effective magnetic field whose strength is proportional to the electron's velocity.