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Title: Effect of heavy metal layer thickness on spin-orbit torque and current-induced switching in Hf|CoFeB|MgO structures

Abstract

We study the heavy metal layer thickness dependence of the current-induced spin-orbit torque (SOT) in perpendicularly magnetized Hf broken vertical bar CoFeB broken vertical bar MgO multilayer structures. The damping-like (DL) current-induced SOT is determined by vector anomalous Hall effect measurements. A non-monotonic behavior in the DL-SOT is found as a function of the thickness of the heavy-metal layer. The sign of the DL-SOT changes with increasing the thickness of the Hf layer in the trilayer structure. As a result, in the current-driven magnetization switching, the preferred direction of switching for a given current direction changes when the Hf thickness is increased above similar to 7 nm. Although there might be a couple of reasons for this unexpected behavior in DL-SOT, such as the roughness in the interfaces and/or impurity based electric potential in the heavy metal, one can deduce a roughness dependence sign reversal in DL-SOT in our trilayer structure.

Authors:
ORCiD logo; ; ORCiD logo; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science - Office of Basic Energy Sciences - Materials Sciences and Engineering Division; National Science Foundation (NSF); U.S. Department of Defense (DOD) - Defense Advanced Research Projects Agency (DARPA)
OSTI Identifier:
1376723
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 109; Journal Issue: 2
Country of Publication:
United States
Language:
English

Citation Formats

Akyol, Mustafa, Jiang, Wanjun, Yu, Guoqiang, Fan, Yabin, Gunes, Mustafa, Ekicibil, Ahmet, Khalili Amiri, Pedram, and Wang, Kang L. Effect of heavy metal layer thickness on spin-orbit torque and current-induced switching in Hf|CoFeB|MgO structures. United States: N. p., 2016. Web. doi:10.1063/1.4958295.
Akyol, Mustafa, Jiang, Wanjun, Yu, Guoqiang, Fan, Yabin, Gunes, Mustafa, Ekicibil, Ahmet, Khalili Amiri, Pedram, & Wang, Kang L. Effect of heavy metal layer thickness on spin-orbit torque and current-induced switching in Hf|CoFeB|MgO structures. United States. doi:10.1063/1.4958295.
Akyol, Mustafa, Jiang, Wanjun, Yu, Guoqiang, Fan, Yabin, Gunes, Mustafa, Ekicibil, Ahmet, Khalili Amiri, Pedram, and Wang, Kang L. Mon . "Effect of heavy metal layer thickness on spin-orbit torque and current-induced switching in Hf|CoFeB|MgO structures". United States. doi:10.1063/1.4958295.
@article{osti_1376723,
title = {Effect of heavy metal layer thickness on spin-orbit torque and current-induced switching in Hf|CoFeB|MgO structures},
author = {Akyol, Mustafa and Jiang, Wanjun and Yu, Guoqiang and Fan, Yabin and Gunes, Mustafa and Ekicibil, Ahmet and Khalili Amiri, Pedram and Wang, Kang L.},
abstractNote = {We study the heavy metal layer thickness dependence of the current-induced spin-orbit torque (SOT) in perpendicularly magnetized Hf broken vertical bar CoFeB broken vertical bar MgO multilayer structures. The damping-like (DL) current-induced SOT is determined by vector anomalous Hall effect measurements. A non-monotonic behavior in the DL-SOT is found as a function of the thickness of the heavy-metal layer. The sign of the DL-SOT changes with increasing the thickness of the Hf layer in the trilayer structure. As a result, in the current-driven magnetization switching, the preferred direction of switching for a given current direction changes when the Hf thickness is increased above similar to 7 nm. Although there might be a couple of reasons for this unexpected behavior in DL-SOT, such as the roughness in the interfaces and/or impurity based electric potential in the heavy metal, one can deduce a roughness dependence sign reversal in DL-SOT in our trilayer structure.},
doi = {10.1063/1.4958295},
journal = {Applied Physics Letters},
number = 2,
volume = 109,
place = {United States},
year = {Mon Jul 11 00:00:00 EDT 2016},
month = {Mon Jul 11 00:00:00 EDT 2016}
}