No abstract

Exchange bias is a property of widespread technological utility, but whose underlying mechanism remains elusive, in part because it is rooted in the interaction of coexisting order parameters in the presence of complex magnetic disorder. Here, we show that a giant exchange bias housed within a spin-glass phase arises in a disordered antiferromagnet. The magnitude and robustness of the exchange bias emerges from a convolution of two energetic landscapes-the highly degenerate landscape of the spin-glass biased by the sublattice spin-configuration of the antiferromagnet. The former provides a source of uncompensated moment, while the latter provides a mechanism for its pinning, leading to the exchange bias. Tuning the relative strength of the spin-glass and antiferromagnet order parameters reveals a principle for tailoring the exchange bias, with potential applications to spintronic technologies.

Recent advances in tuning the correlated behavior of graphene and transition-metal dichalcogenides (TMDs) have opened a new frontier in the study of many-body physics in two dimensions and promise exciting possibilities for new quantum technologies. An emerging field where these materials have yet to make a deep impact is the study of antiferromagnetic (AFM) spintronics -a relatively new research direction that promises technologies that are insensitive to external magnetic fields, fast switching times, and reduced crosstalk [1][2][3] . In this study we present measurements on the intercalated TMD Fe1/3NbS2 which exhibits antiferromagnetic ordering below 42K 4,5 . We find that current densities on the order of 10 4 A/cm 2 can reorient the magnetic order, the response of which can be detected in the sample's resistance. This demonstrates that Fe1/3NbS2 can be used as an antiferromagnetic switch with electronic "write-in" and "read-out". This switching is found to be stable over time and remarkably robust to external magnetic fields. Fe1/3NbS2 is a rare example of an AFM system that exhibits fully electronic switching behavior in single crystal form, making it appealing for low-power, low-temperature memory storage applications. Moreover, Fe1/3NbS2 is part of a much larger family of magnetically intercalated TMDs, some of which may exhibit the switching behavior at higher temperatures and form a platform from which to build tunable AFM spintronic devices 6,7 .AFM memory storage devices have been long sought-after in the field of spintronics. Compared to the their widely used ferromagnetic (FM) counterparts, AFM memory promises several key improvements. AFMs do not produce external stray fields, making memory stored in these devices invisible to external magnetic probes and allowing individual devices to be more tightly packed on-chip 1,2 . They possess ultrafast spin dynamics; AFM devices have been recently demonstrated to switch at THz speeds, significantly faster than their GHz-limited FM counterparts 3,8 . Finally, they couple weakly to external magnetic fields, making AFM devices robust to magnetic perturbations. Combined, these properties make AFMs appealing for highdensity, ultrafast, extremely stable memory storage applications. Their insensitivity to field, however, makes manipulating and detecting AFMs difficult, limiting their widespread adoption primarily to passive layers in FM heterostructure devices 9,10 . Only two examples have emerged in which the AFM order can be demonstrably manipulated and detected by applied currents: CuMnAs and Mn2Au 11,12 .