Aug 28 – 31, 2018
EPFL
Europe/Zurich timezone

【814】 Spin-orbit torque induced domain switching in antiferromagnet/ferromagnet heterostructures

Aug 30, 2018, 3:00 PM
15m
CE 1 (EPFL)

CE 1

EPFL

Talk Magnetism and Spintronics at the Nanoscale Magnetism and Spintronics at the Nanoscale

Speaker

Gunasheel Krishnaswamy (Department of Materials, ETH Zürich)

Description

Recently, current-induced spin-orbit torques(SOT) switching have been demonstrated in ferromagnet(FM) / antiferromagnet(AFM) multilayers with perpendicular anisotropy [1,2]. The use of an AFM results in multiple nonvolatile (memristive) states, akin to neural networks [3]. Past experiments suggest that the non-uniform exchange bias from the AFM causes separate switching of domains, leading to this behavior [4]. This description differs from conventional SOT switching in FM/nonmagnet (NM) cases [5]. A deeper understanding of the switching in FM/AFM structures is thus relevant for SOT research and for AFM applications in spintronic devices. Here we use x-ray photoemission electron microscopy to image the FM domains of [Co/Ni]2/PtMn layers, at intermediate switching states with injected currents. We find that the Co/Ni domains are shaped irregularly and are of the order of 300 nm. Sequential current pulses gradually switch domains by nucleation & expansion, reproducibly; commensurate with electrical measurements. As a 1st visualization of field-free SOT switching, this opens new avenues to understand and optimize this behavior for FM/AFM spintronics devices.
(Work supported by CSTI-ImPACT, JST-OPERA & the Swiss NSF)

[1] S.Fukami et al., Nat.Mater. 15,535 (2016).
[2] A.van den Brink et al., Nat.Comm. 7,10854 (2016).
[3] W. A. Borders et. al., Appl.Phys.Express 10,013007 (2017).
[4] A. Kurenkov et al., Appl.Phys.Lett. 110,092410 (2017).
[5] M.Baumgartner et al., Nat.Nanotech. 12,980 (2017).

Primary authors

Gunasheel Krishnaswamy (Department of Materials, ETH Zürich) Manuel Baumgartner (ETH Zürich) Giacomo Sala (Department of Materials, ETH Zürich) A. Kurenkov (Laboratory for Nanoelectronics and Spintronics, RIEC, Tohoku University) F. Maccherozzi (Diamond Light Source) S. Fukami H. Ohno Prof. Pietro Gambardella (ETH Zurich)

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