Collimation of electrons at closed magnetic barriers in two-dimensional electron gases

It is shown that closed magnetic barriers defined in two-dimensional electron gases generate a collimated emerging electron beam at the edge of the Hall bar. The collimation takes place through two mechanisms: electron selection for $\stackrel{P\vec}{E}\ifmmode\times\else\texttimes\fi{}\stackrel{P\vec}{B}$ drift at the edge and bulk collimation of the emerging electrons due to the magnetic field gradient. The collimation effect is verified by experiments and simulations: a second magnetic barrier used as a probe will reflect the collimated beam differently when positioned at various distances from the first one, resulting in oscillations in the resistance.