Large Anomalous Unidirectional Magnetoresistance in a Single Ferromagnetic Layer

Unidirectional magnetoresistance (UMR) in a ferromagnetic bilayer due to the spin Hall effect (SHE) provides facile means of probing in-plane magnetization avoid complex magnetic tunnel junctions. However, UMR signal is very weak and usually requires lock-in amplifier for detection, even involving $\mathrm{Ta}$ or $\mathrm{Pt}$ with large angle (SHA). Here, we report type UMR, termed anomalous (AUMR), single $\mathrm{Co}\text{\ensuremath{-}}\mathrm{Fe}\text{\ensuremath{-}}\mathrm{B}$ layer without any adjacent SHE layers, where about 10 times larger than that $\mathrm{Ta}/\mathrm{Co}\text{\ensuremath{-}}\mathrm{Fe}\text{\ensuremath{-}}\mathrm{B}$ structures can be detected by using conventional dc multimeters absence amplifiers. We further demonstrate extracted AUMR, excluding thermal contributions, shows reversal signs $\mathrm{Ni}\text{\ensuremath{-}}\mathrm{Fe}$ layers opposite SHAs, indicating AUMR may originate from self-generated accumulation interacting through giant-magnetoresistance-like mechanism. These results suggest contributes signals interfacial $\mathrm{Co}\text{\ensuremath{-}}\mathrm{Fe}\text{\ensuremath{-}}\mathrm{B}$-based systems, providing convenient reliable approach detect two-terminal spintronic devices.