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Anisotropic spin-orbit torque generation in epitaxial SrIrO3 by symmetry design

Cornell Affiliated Author(s)

Author

T. Nan
T. Anderson
J. Gibbons
K. Hwang
N. Campbell
H. Zhou
Y. Dong
G . Y. Kim
D. Shao
T. Paudel
N. Reynolds
X. Wang
N. Sun
E . Y. Tsymbal
S . Y. Choi
M. Rzchowski
Yong Kim
D. Ralph
C. Eom

Abstract

Spin-orbit coupling (SOC), the interaction between the electron spin and the orbital angular momentum, can unlock rich phenomena at interfaces, in particular interconverting spin and charge currents. Conventional heavy metals have been extensively explored due to their strong SOC of conduction electrons. However, spin-orbit effects in classes of materials such as epitaxial 5d-electron transition-metal complex oxides, which also host strong SOC, remain largely unreported. In addition to strong SOC, these complex oxides can also provide the additional tuning knob of epitaxy to control the electronic structure and the engineering of spin-to-charge conversion by crystalline symmetry. Here, we demonstrate room-temperature generation of spin-orbit torque on a ferromagnet with extremely high efficiency via the spin-Hall effect in epitaxial metastable perovskite SrIrO3. We first predict a large intrinsic spin-Hall conductivity in orthorhombic bulk SrIrO3 arising from the Berry curvature in the electronic band structure. By manipulating the intricate interplay between SOC and crystalline symmetry, we control the spin-Hall torque ratio by engineering the tilt of the corner-sharing oxygen octahedra in perovskite SrIrO3 through epitaxial strain. This allows the presence of an anisotropic spin-Hall effect due to a characteristic structural anisotropy in SrIrO3 with orthorhombic symmetry. Our experimental findings demonstrate the heteroepitaxial symmetry design approach to engineer spin-orbit effects. We therefore anticipate that these epitaxial 5d transition-metal oxide thin films can be an ideal building block for low-power spintronics. © 2019 National Academy of Sciences. All rights reserved.

Date Published

Journal

Proceedings of the National Academy of Sciences

Volume

116

Issue

33

Number of Pages

16186-16191,

URL

https://www.scopus.com/inward/record.uri?eid=2-s2.0-85070630350&doi=10.1073%2fpnas.1812822116&partnerID=40&md5=5cf0195ae02533fee23b72aa59eb45d2

DOI

10.1073/pnas.1812822116

Funding Source

DE-FG02-06ER46327
1160504
1708499
1719875
DMR-1629270
FA9550-15-1-0334
W911NF-17-1-0462
DE-AC02-06CH11357
DMR-1708499
DMR-1719875

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