Spin-neutral currents for spintronics

Ding-Fu Shao; Shu-Hui Zhang; Ming Li; Chang-Beom Eom; Evgeny Y Tsymbal

doi:10.1038/s41467-021-26915-3

Spin-neutral currents for spintronics

Nat Commun. 2021 Dec 3;12(1):7061. doi: 10.1038/s41467-021-26915-3.

Authors

Ding-Fu Shao¹, Shu-Hui Zhang², Ming Li³, Chang-Beom Eom⁴, Evgeny Y Tsymbal⁵

Affiliations

¹ Department of Physics and Astronomy & Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE, 68588-0299, USA. dfshao@unl.edu.
² College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing, 100029, People's Republic of China.
³ Department of Physics and Astronomy & Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE, 68588-0299, USA.
⁴ Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, 3706, US.
⁵ Department of Physics and Astronomy & Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE, 68588-0299, USA. tsymbal@unl.edu.

Abstract

Electric currents carrying a net spin polarization are widely used in spintronics, whereas globally spin-neutral currents are expected to play no role in spin-dependent phenomena. Here we show that, in contrast to this common expectation, spin-independent conductance in compensated antiferromagnets and normal metals can be efficiently exploited in spintronics, provided their magnetic space group symmetry supports a non-spin-degenerate Fermi surface. Due to their momentum-dependent spin polarization, such antiferromagnets can be used as active elements in antiferromagnetic tunnel junctions (AFMTJs) and produce a giant tunneling magnetoresistance (TMR) effect. Using RuO₂ as a representative compensated antiferromagnet exhibiting spin-independent conductance along the [001] direction but a non-spin-degenerate Fermi surface, we design a RuO₂/TiO₂/RuO₂ (001) AFMTJ, where a globally spin-neutral charge current is controlled by the relative orientation of the Néel vectors of the two RuO₂ electrodes, resulting in the TMR effect as large as ~500%. These results are expanded to normal metals which can be used as a counter electrode in AFMTJs with a single antiferromagnetic layer or other elements in spintronic devices. Our work uncovers an unexplored potential of the materials with no global spin polarization for utilizing them in spintronics.

Abstract

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