Magnetic tunnel junctions and magnetic logic circuits driven by spin-orbit torques*

Current-induced spin-orbit torques (SOTs) enable the switching of magnetic tunnel junctions (MTJs) in nonvolatile magnetic random access memories as well as the all-electrical operation of magnetic logic circuits based on domain wall manipulation. This talk will present time-resolved measurements of magnetization reversal driven by SOTs in 3-terminal MTJ devices and show how the combination of SOT, spin transfer torque, and voltage control of magnetic anisotropy leads to reproducible sub-ns magnetization reversal with a very narrow spread of the switching time distributions [1, 2]. Further, it will be shown how SOTs and the chiral coupling between neighbouring magnetic domains induced by the interfacial Dzyaloshinskii–Moriya interaction [3] allow for realizing an electrically-driven domain-wall inverter. Starting from this basic building block, it is possible to fabricate reconfigurable NAND and NOR logic gates, and therefore a complete family of logic gates, which perform operations with current-induced domain-wall motion [4]. Opportunities for scalable all-electric magnetic memories and memory-in-logic applications will be discussed.

[1] E. Grimaldi, V. Krizakova, G. Sala, F. Yasin, S. Couet, G. S. Kar, K. Garello and P Gambardella, Nat. Nanotech. 15, 111 (2020).
[2] V. Krizakova et al., Appl. Phys. Lett. 116, 232406 (2020).
[3] Z. Luo, T. Phuong Dao, A. Hrabec, J. Vijayakumar, A. Kleibert, M. Baumgartner, E. Kirk, J. Cui, T. Savchenko, G. Krishnaswamy, L. J. Heyderman, and P. Gambardella, Science 363, 1435 (2019).
[4] Z. Luo, A. Hrabec, T. P. Dao, G. Sala, S. Finizio, J. Feng, S. Mayr, J. Raabe, P. Gambardella, L. J. Heyderman, Nature 579, 214 (2020).