Vol. 51 (2020) Acta Physica Polonica B No 4THE KLEIN PARADOX IN A MAGNETIC FIELD:EFFECTS OF ELECTRON SPINWlodek Zawadzki, Pawel PfefferInstitute of Physics, Polish Academy of SciencesAl. Lotnikow 32/46, 02-668 Warsaw, Poland(Received January 20, 2020; accepted March 4, 2020)Reflection and transmission of electrons scattered by a rectangular po-tential step in the presence of an external magnetic field parallel to theelectron beam is described with the use of the Dirac equation. It is shownthat i...