Electrical manipulation of the magnetic order in antiferromagnetic PtMn pillars

Abstract

Antiferromagnets are magnetically ordered materials without a macroscopic magnetization. As a result, they could be of use in the development of memory devices because data cannot be erased by external magnetic fields. However, this also makes it difficult to electrically control their magnetic order (Néel vector). Here, we show that pillars of antiferromagnetic PtMn, which are grown on a heavy-metal layer and have diameters down to 800 nm, can be reversibly switched between different magnetic states by electric currents. The devices are based on materials that are typically used in the magnetic memory industry, and we observe switching down to a current density of ~2 MA cm−2. Furthermore, by varying the amplitude of the writing current, multilevel memory characteristics can be achieved. Micromagnetic simulations suggest that the different magnetic states may consist of domains separated by domain walls with vortex and anti-vortex textures that move in response to current, modifying the average Néel vector.

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Fig. 1: Device structure.
Fig. 2: Current-controlled switching measurements.
Fig. 3: Micromagnetic simulations.
Fig. 4: Switching experiment with an asymmetric number of write pulses.
Fig. 5: Switching results for different AFM film thickness and heavy-metal materials.
Fig. 6: Current-controlled switching measurements on nanometre-scale devices.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding authors upon reasonable request.

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Acknowledgements

This work was supported by a grant from the National Science Foundation, Division of Electrical, Communications and Cyber Systems (NSF ECCS-1853879), and in part by the Air Force Office of Scientific Research (AFOSR FA9550-15-1-0377). This work also utilized the Northwestern University Micro/Nano Fabrication Facility (NUFAB), which is partially supported by the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205), the Materials Research Science and Engineering Center (DMR-1720139), the State of Illinois and Northwestern University. For part of the sample fabrication, use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract no. DE-AC02-06CH11357. G.F. and F.G. also acknowledge support from PETASPIN.

Author information

J.S., V.L.-D., H.A., G.F. and P.K.A. designed the devices. V.L.-D., J.S. and H.A. deposited the materials. J.S. fabricated the devices. V.L.-D., J.S. and C.W. performed the measurements. F.G. and G.F. performed the micromagnetic simulations. P.K.A., G.F., V.L.-D. and J.S. wrote the manuscript with contributions from the other authors. All authors discussed the results, contributed to the data analysis and commented on the manuscript. J.S. and V.L.-D. contributed equally to this research. The study was performed under the supervision of P.K.A.

Correspondence to Giovanni Finocchio or Pedram Khalili Amiri.

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Supplementary Information

Supplementary Information

Supplementary Notes 1–8 and Figs. 1–9.

Supplementary Video 1

The time-domain evolution of the spatial distribution of the Néel vector for the simulation described in Fig. 3b.

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Shi, J., Lopez-Dominguez, V., Garesci, F. et al. Electrical manipulation of the magnetic order in antiferromagnetic PtMn pillars. Nat Electron 3, 92–98 (2020). https://doi.org/10.1038/s41928-020-0367-2

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