Giant coercivity in perpendicularly magnetized cobalt monolayer

Abstract

We report giant coercivity (HC) up to 35 kOe at 4 K, measured by the anomalous Hall effect, in perpendicularly magnetized Co (∼0.3 nm) films, where Co is approximately one monolayer. The HC is dramatically reduced with huge applied current, due to Joule heating rather than Rashba effect. It is also sensitive to temperatures, producing almost zero HC at 200 K. The Curie temperature of the Co monolayer is ∼275 K, far lower than that of bulk Co. The giant HC could be explained by the strong interaction at Co/Pd interface, providing a promising paradise: one monolayer, one permanent magnet.