Giant interfacial in-plane magnetic anisotropy in Co/Pt bilayers grown on MgO(110) substrates

Strong magnetic anisotropy is crucial for spintronic devices, but the strength of in-plane anisotropy (IMA) has constrained its applications in magnetic storage devices in contrast with the perpendicular magnetic anisotropy (PMA). In our study, we observed a giant interfacial uniaxial IMA in Co/Pt(110) bilayers that is approximately five times larger than the PMA in Co/Pt(111) systems. By adding another interface to form Pt/Co/Pt trilayers, the total interfacial uniaxial IMA can be further enhanced to $13.1\pm 0.3\mathrm{erg}/{\mathrm{cm}}^2$, making it a promising platform for high-density storage devices. The interfacial IMA in Co/Pt(110) bilayers is related to the Co at the interface and can be controlled by inserting an ultrathin Cu layer. Our results demonstrated the strong in-plane anisotropy in Co/Pt(110) systems, making it a promising platform for studying the spintronic phenomenon in strongly anisotropic systems.