Title: Tuning Spin‐Orbit Torques Across the Phase Transition in VO ₂ /NiFe Heterostructure

Abstract

The emergence of spin-orbit torques as a promising approach to energy-efficient magnetic switching has generated large interest in material systems with easily and fully tunable spin-orbit torques. We report current-induced spin-orbit torques in VO₂/NiFe heterostructures are investigated using spin-torque ferromagnetic resonance, where the VO₂ layer undergoes a prominent insulator-metal transition. A roughly twofold increase in the Gilbert damping parameter, α, with temperature is attributed to the change in the VO₂/NiFe interface spin absorption across the VO₂ phase transition. More remarkably, a large modulation (±100%) and a sign change of the current-induced spin-orbit torque across the VO₂ phase transition suggest two competing spin-orbit torque generating mechanisms. The bulk spin Hall effect in metallic VO₂, corroborated by the first-principles calculation of the spin Hall conductivity σ_SH ≈ -10⁴ ($$\frac{\hbar}{e}$$) Ω^-1 m^-1 , is verified as the main source of the spin-orbit torque in the metallic phase. The self-induced/anomalous torque in NiFe, with opposite sign and a similar magnitude to the bulk spin Hall effect in metallic VO₂, can be the other competing mechanism that dominates as temperature decreases. For applications, the strong tunability of the torque strength and direction opens a new route to tailor spin-orbit torques of materials that undergo phase transitions for new device functionalities.

Authors:

Kim, Jun‐young  ^[1];

• Search DOE PAGES for author "Kim, Jun‐young"
• Search DOE PAGES for ORCID "0000-0002-1639-3270"

Cramer, Joel ^[2]; Lee, Kyujoon ^[3]; Han, Dong‐Soo ^[4]; Go, Dongwook ^[5]; Salev, Pavel ^[6]; Lapa, Pavel N. ^[6]; Vargas, Nicolas M. ^[6]; Schuller, Ivan K. ^[6]; Mokrousov, Yuriy ^[5]; Jakob, Gerhard ^[2]; Kläui, Mathias  ^[2]

• Search DOE PAGES for author "Kläui, Mathias"
• Search DOE PAGES for ORCID "0000-0002-4848-2569"

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+ Show Author Affiliations

1. Institute of Physics Johannes Gutenberg University Mainz 55128 Germany, Max Planck Institute for Intelligent Systems Stuttgart 70569 Germany
2. Institute of Physics Johannes Gutenberg University Mainz 55128 Germany
3. Institute of Physics Johannes Gutenberg University Mainz 55128 Germany, Department of Semiconductor Physics Korea University Sejong 30019 Republic of Korea
4. Institute of Physics Johannes Gutenberg University Mainz 55128 Germany, Korea Institute of Science and Technology Seoul 02792 Republic of Korea
5. Institute of Physics Johannes Gutenberg University Mainz 55128 Germany, Peter Grünberg Institut and Institute for Advanced Simulation Forschungszentrum Jülich and JARA Jülich 52425 Germany
6. Department of Physics and Center for Advanced Nanoscience University of California San Diego La Jolla CA 92093 USA

Publication Date:

Mon Jan 17 00:00:00 EST 2022

Research Org.:

Univ. of California, San Diego, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); German Research Foundation (DFG); Horizon 2020; European Commission (EC); National Research Foundation of Korea (NRF); National Research Council of Science & Technology (NST); Korea University Grant

OSTI Identifier:

1840621

Alternate Identifier(s):

OSTI ID: 1840622; OSTI ID: 1976186

Grant/Contract Number:  

DE FG02 87ER‐45332; FG02-87ER45332; 863155; 856538; 2020R1C1C1012664; 2019M3F3A1A02071509; CAP-16-01-KIST; K2111401

Resource Type:

Published Article

Journal Name:

Advanced Functional Materials

Additional Journal Information:

Journal Name: Advanced Functional Materials Journal Volume: 32 Journal Issue: 17; Journal ID: ISSN 1616-301X

Publisher:

Wiley Blackwell (John Wiley & Sons)

Country of Publication:

Germany

Language:

English

Subject:

36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; current-induced spin-orbit torque; insulator-metal transition; spin-torque ferromagnetic resonance; vanadium dioxide