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Author |
Sethu, K.K.V.; Yasin, F.; Swerts, J.; Sorée, B.; De Boeck, J.; Kar, G.S.; Garello, K.; Couet, S. |
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Title |
Spin-orbit torque vector quantification in nanoscale magnetic tunnel junctions |
Type |
A1 Journal article |
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Year |
2024 |
Publication |
ACS nano |
Abbreviated Journal |
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Volume |
18 |
Issue |
21 |
Pages |
13506-13516 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
Spin-orbit torques (SOT) allow ultrafast, energy-efficient toggling of magnetization state by an in-plane charge current for applications such as magnetic random-access memory (SOT-MRAM). Tailoring the SOT vector comprising of antidamping (T-AD) and fieldlike (T-FL) torques could lead to faster, more reliable, and low-power SOT-MRAM. Here, we establish a method to quantify the longitudinal (T-AD) and transverse (T-FL) components of the SOT vector and its efficiency chi(AD) and chi(FL), respectively, in nanoscale three-terminal SOT magnetic tunnel junctions (SOT-MTJ). Modulation of nucleation or switching field (B-SF) for magnetization reversal by SOT effective fields (B-SOT) leads to the modification of SOT-MTJ hysteresis loop behavior from which chi(AD) and chi(FL) are quantified. Surprisingly, in nanoscale W/CoFeB SOT-MTJ, we find chi(FL) to be (i) twice as large as chi(AD) and (ii) 6 times as large as chi(FL) in micrometer-sized W/CoFeB Hall-bar devices. Our quantification is supported by micromagnetic and macrospin simulations which reproduce experimental SOT-MTJ Stoner-Wohlfarth astroid behavior only for chi(FL) > chi(AD). Additionally, from the threshold current for current-induced magnetization switching with a transverse magnetic field, we show that in SOT-MTJ, T-FL plays a more prominent role in magnetization dynamics than T-AD. Due to SOT-MRAM geometry and nanodimensionality, the potential role of nonlocal spin Hall spin current accumulated adjacent to the SOT-MTJ in the mediation of T-FL and chi(FL) amplification merits to be explored. |
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Wos |
001226121700001 |
Publication Date |
2024-05-15 |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1936-0851 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
17.1 |
Times cited |
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Open Access |
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Notes |
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Approved |
Most recent IF: 17.1; 2024 IF: 13.942 |
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Call Number |
UA @ admin @ c:irua:205980 |
Serial |
9173 |
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Permanent link to this record |
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Author |
Sethu, K.K.V.; Ghosh, S.; Couet, S.; Swerts, J.; Sorée, B.; De Boeck, J.; Kar, G.S.; Garello, K. |
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Title |
Optimization of tungsten beta-phase window for spin-orbit-torque magnetic random-access memory |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Physical Review Applied |
Abbreviated Journal |
Phys Rev Appl |
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Volume |
16 |
Issue |
6 |
Pages |
064009 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Switching induced by spin-orbit torque (SOT) is being vigorously explored, as it allows the control of magnetization using an in-plane current, which enables a three-terminal magnetic-tunnel-junction geometry with isolated read and write paths. This significantly improves the device endurance and the read stability, and allows reliable subnanosecond switching. Tungsten in the beta phase, beta-W, has the largest reported antidamping SOT charge-to-spin conversion ratio (theta(AD) approximate to -60%) for heavy metals. However, beta-W has a limitation when one is aiming for reliable technology integration: the beta phase is limited to a thickness of a few nanometers and enters the alpha phase above 4 nm in our samples when industry-relevant deposition tools are used. Here, we report our approach to extending the range of beta-W, while simultaneously improving the SOT efficiency by introducing N and O doping of W. Resistivity and XRD measurements confirm the extension of the beta phase from 4 nm to more than 10 nm, and transport characterization shows an effective SOT efficiency larger than -44.4% (reaching approximately -60% for the bulk contribution). In addition, we demonstrate the possibility of controlling and enhancing the perpendicular magnetic anisotropy of a storage layer (Co-Fe-B). Further, we integrate the optimized W(O, N) into SOT magnetic random-access memory (SOT-MRAM) devices and project that, for the same thickness of SOT material, the switching current decreases by 25% in optimized W(O, N) compared with our standard W. Our results open the path to using and further optimizing W for integration of SOT-MRAM technology. |
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Wos |
000729005800002 |
Publication Date |
2021-12-03 |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2331-7019 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.808 |
Times cited |
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Open Access |
Not_Open_Access |
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Notes |
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Approved |
Most recent IF: 4.808 |
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Call Number |
UA @ admin @ c:irua:184832 |
Serial |
7007 |
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Permanent link to this record |