Electrical switching in a magnetically intercalated transition metal dichalcogenide

Abstract

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 .

Half-magnetization plateau and the origin of threefold symmetry breaking in an electrically switchable triangular antiferromagnet

“…The symmetry constraints of the switching reported in Ref. [3] also indicate an in-plane component to the moment at zero field which is not accounted for in this model. To capture the remaining fine features of Fe 1/3 NbS 2 would require a more sophisticated 3D model with vastly more parameters and temperature effects, similar to those in Refs.…”

“…In this work, we study magnetization plateaus in the antiferromagnet Fe 1/3 NbS 2 , a magnetically intercalated transition metal dichalcogenide which has recently been found to exhibit reversible, electrically stimulated switching between stable magnetic states [3]. This behavior has been seen with considerably lower energy requirements in Fe 1/3 NbS 2 as compared to the other systems [3], raising the question of whether the mechanism differs significantly [4,5].…”

“…In this work, we study magnetization plateaus in the antiferromagnet Fe 1/3 NbS 2 , a magnetically intercalated transition metal dichalcogenide which has recently been found to exhibit reversible, electrically stimulated switching between stable magnetic states [3]. This behavior has been seen with considerably lower energy requirements in Fe 1/3 NbS 2 as compared to the other systems [3], raising the question of whether the mechanism differs significantly [4,5]. At the center of this question is the nature of the magnetic ground state, which has been challenging to determine because collinear and noncollinear order are energetically close and the true ground state depends strongly on the magnetocrystalline anisotropy [6].…”

Giant anomalous Hall effect in quasi-two-dimensional layered antiferromagnet Co1/3NbS2

“…Viable strategies to change the electron density by a significant amount include the use of ionic liquid gated devices, if the thickness of Co 1/3 NbS 2 can be reduced to a few layers, or intercalation of atoms (either alkali or halogen) in between the NbS 2 planes (i.e., where the Co atoms also reside). Yet another route consists in investigating other NbS 2 -based compounds intercalated with different transition metals: Fe 1/3 NbS 2 for instance is also an antiferromagnetic conductor [48,49], with a different expected band filling as compared to Co 1/3 NbS 2 , owing to the difference valence of Fe as compared to Co atoms. Although challenging experimentally, all these different strategies are worth considering because, if successful, they would allow unveiling a quantum anomalous Hall antiferromagnet, i.e., an exotic state of matter that has never been observed before.…”

Intercalated phases of transition metal dichalcogenides

“…33 Intercalation modifies the properties of TMD by a myriad of effects, including charge doping, [34][35][36] expansion of c axis lattice constants, [37][38][39][40] orbital hybridization, [41][42][43] and phonon scattering. 37,44,45 A wide range of properties could be promoted or tuned, from electrical conductivity, 46,47 optical modes, 48,49 magnetic order, 43,50 thermoelectricity, 45,51 catalytic activities, 52,53 to energy storage and conversion performances. 30,31 Moreover, the concentration of the intercalant can have a threshold effect in ferroic or charge orders.…”