Nature Nanotechnology 11, 449–454 (2016); published online 25 January 2016; corrected after print 18 July 2017

In the version of this Article originally published, the Dzyaloshinskii–Moriya interaction parameter, D, should have been multiplied by √3. The vertical scale of Fig. 2 has been updated accordingly as has the following sentence concerning D values: “For 5 monolayers (ML) of Co, equivalent to a total Co thickness of 1 nm, the ab initio calculations predict = 4.0 mJ m−2 whereas a lower value D = 2.6 mJ m−2 is predicted for a Pt/Co/vacuum structure.” Additionally the Methods and Supplementary Information have been updated to correct the experimental multilayer composition to: “Ta(3)/Pt(3)/Co(0.5−1)/MgOx/Ta(2) (thickness in nm)”.