Unusual Angular Dependent Magnetoresistance In Single-Crystalline Co/Pt Bilayers

The magnetoresistance (MR) of the single-crystalline Co/Pt(111) bilayers was studied systematically as a function of Co or Pt thickness at room temperature. For Co thickness d(Co) < 6 nm, the resistances with in-plane magnetization M parallel (R-parallel to) and transverse (R-perpendicular to) to current and with a perpendicular M normal (R-P) to film show the unconventional behavior of R-P > R-parallel to > R-perpendicular to. This MR behavior can be attributed to the combination effect of spin Hall MR with R-P approximate to R-parallel to > R-perpendicular to and the geometrical size effect. In addition, the angular dependent magnetoresistance behavior of the (111)-oriented Co/Pt bilayer shows striking difference with that of the (001)-oriented Co/Pt bilayer. Published by AIP Publishing.