Single crystal epitaxial [Co/CoO]n superlattices consisting of ferromagnetic metal and antiferromagnetic insulator

Abstract

Heterostructures consisting of ferromagnetic metal and antiferromagnetic insulator have exhibited novel properties in interface exchange coupling, magnetoresistance and spin injection due to their fundamental physics of magnetism. However, as compared with bilayer heterostructures, it is very challenging in experiments to prepare single crystal epitaxial ultrathin superlattices consisting of ferromagnetic metal and antiferromagnetic insulator, where the interface exchange coupling, magnetic order, and electrical transport properties are expected to be greatly modulated due to the multiple interfaces and periodical structures. Here we prepared single crystal epitaxial [Co/CoO]n superlattices consisting of ferromagnetic metal Co and antiferromagnetic insulator CoO by molecular beam epitaxy. It is found that the saturation magnetization of [Co 0.6 nm/CoO 1.2 nm]5 superlattice is robust against temperature increase, which only shows a slight decrease of 1.5% from 5 K to 300 K. Moreover, we found that the longitudinal resistivity and anomalous Hall resistivity of [Co/CoO]n superlattices are strongly modulated by the short-period Co/CoO heterostructure, which are quite distinguished from the electrical transport properties of Co bulk ferromagnetic metal. The [Co/CoO]n superlattices provide a new insight into heterostructures consisting of ferromagnetic metal and antiferromagnetic insulator, which are beneficial for designing future spintronics devices.