|
Records |
Links |
|
Author |
Couet, S.; Peelaers, H.; Trekels, M.; Houben, K.; Petermann, C.; Hu, M.Y.; Zhao, J.Y.; Bi, W.; Alp, E.E.; Menéndez, E.; Partoens, B.; Peeters, F.M.; Van Bael, M.J.; Vantomme, A.; Temst, K.; |
![goto web page (via DOI) doi](http://nano.uantwerpen.be/nanorefs/img/doi.gif)
|
|
Title |
Interplay between lattice dynamics and superconductivity in Nb3Sn thin films |
Type |
A1 Journal article |
|
Year |
2013 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
|
|
Volume |
88 |
Issue |
4 |
Pages |
045437-7 |
|
|
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
|
|
Abstract |
We investigate the link between superconductivity and atomic vibrations in Nb3Sn films with a thickness ranging from 10 to 50 nm. The challenge of measuring the phonon density of states (PDOS) of these films has been tackled by employing the technique of nuclear inelastic scattering by Sn-119 isotopes to reveal the Sn-partial phonon density of states. With the support of ab initio calculations, we evaluate the effect of reduced film thickness on the PDOS. This approach allows us to estimate the changes in superconducting critical temperature T-c induced by phonon confinement, which turned out to be limited to a few tenths of K. The presented method is successful for the Nb3Sn system and paves the way for more systematic studies of the role of phonon confinement in Sn-containing superconductors. |
|
|
Address |
|
|
|
Corporate Author |
|
Thesis ![sorted by Thesis field, ascending order (up)](img/sort_asc.gif) |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Wos |
000322529900004 |
Publication Date |
2013-07-27 |
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
3.836 |
Times cited |
5 |
Open Access |
|
|
|
Notes |
; The authors would like to cordially thank Dr. Rudolf Ruffer from the nuclear resonant scattering group of the ESRF for the support and gratefully acknowledge the ESRF for providing beamtime for the preliminary phonon study. S. C., K. H., and E. M. thank the Flemish Science Foundation (FWO-Vl) for their personal fellowship. This work was supported by FWO-Vl, the Methusalem program of the Flemish government, and the Concerted Research Action program (GOA/09/ 006) and (GOA/14/007). Use of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357. ; |
Approved |
Most recent IF: 3.836; 2013 IF: 3.664 |
|
|
Call Number |
UA @ lucian @ c:irua:109801 |
Serial |
1702 |
|
Permanent link to this record |
|
|
|
|
Author |
Sankaran, K.; Swerts, J.; Couet, S.; Stokbro, K.; Pourtois, G. |
![goto web page (via DOI) doi](http://nano.uantwerpen.be/nanorefs/img/doi.gif)
|
|
Title |
Oscillatory behavior of the tunnel magnetoresistance due to thickness variations in Ta vertical bar CoFe vertical bar MgO magnetic tunnel junctions : a first-principles study |
Type |
A1 Journal article |
|
Year |
2016 |
Publication |
Physical review B |
Abbreviated Journal |
Phys Rev B |
|
|
Volume |
94 |
Issue |
94 |
Pages |
094424 |
|
|
Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
|
|
Abstract |
To investigate the impact of both the CoFe ferromagnetic layer thickness and the capping paramagnetic layer on the tunnel magnetoresistance (TMR), we performed first-principles simulations on epitaxial magnetic tunnel junctions contacted with either CoFe or Ta paramagnetic capping layers. We observed a strong oscillation of the TMR amplitude with respect to the thickness of the ferromagnetic layer. The TMR is found to be amplified whenever the MgO spin tunnel barrier is thickened. Quantization of the electronic structure of the ferromagnetic layers is found to be at the origin of this oscillatory behavior. Metals such as Ta contacting the magnetic layer are found to enhance the amplitude of the oscillations due to the occurrence of an interface dipole. The latter drives the band alignment and tunes the nature of the spin channels that are active during the tunneling process. Subsequently, the regular transmission spin channels are modulated in the magnetic tunnel junction stack and other complex ones are being activated. |
|
|
Address |
|
|
|
Corporate Author |
|
Thesis ![sorted by Thesis field, ascending order (up)](img/sort_asc.gif) |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Wos |
000383860700004 |
Publication Date |
2016-09-20 |
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
2469-9950;2469-9969; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
3.836 |
Times cited |
4 |
Open Access |
|
|
|
Notes |
|
Approved |
Most recent IF: 3.836 |
|
|
Call Number |
UA @ lucian @ c:irua:137122 |
Serial |
4468 |
|
Permanent link to this record |
|
|
|
|
Author |
Houben, K.; Couet, S.; Trekels, M.; Menendez, E.; Peissker, T.; Seo, J.W.; Hu, M.Y.; Zhao, J.Y.; Alp, E.E.; Roelants, S.; Partoens, B.; Milošević, M.V.; Peeters, F.M.; Bessas, D.; Brown, S.A.; Vantomme, A.; Temst, K.; Van Bael, M.J. |
![goto web page (via DOI) doi](http://nano.uantwerpen.be/nanorefs/img/doi.gif)
|
|
Title |
Lattice dynamics in Sn nanoislands and cluster-assembled films |
Type |
A1 Journal article |
|
Year |
2017 |
Publication |
Physical review B |
Abbreviated Journal |
Phys Rev B |
|
|
Volume |
95 |
Issue |
15 |
Pages |
155413 |
|
|
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
|
|
Abstract |
To unravel the effects of phonon confinement, the influence of size and morphology on the atomic vibrations is investigated in Sn nanoislands and cluster-assembled films. Nuclear resonant inelastic x-ray scattering is used to probe the phonon densities of states of the Sn nanostructures which show significant broadening of the features compared to bulk phonon behavior. Supported by ab initio calculations, the broadening is attributed to phonon scattering and can be described within the damped harmonic oscillator model. Contrary to the expectations based on previous research, the appearance of high-energy modes above the cutoff energy is not observed. From the thermodynamic properties extracted from the phonon densities of states, it was found that grain boundary Sn atoms are bound by weaker forces than bulk Sn atoms. |
|
|
Address |
|
|
|
Corporate Author |
|
Thesis ![sorted by Thesis field, ascending order (up)](img/sort_asc.gif) |
|
|
|
Publisher |
American Physical Society |
Place of Publication |
New York, N.Y |
Editor |
|
|
|
Language |
|
Wos |
000401762400008 |
Publication Date |
2017-04-11 |
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
2469-9969; 2469-9950 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
3.836 |
Times cited |
5 |
Open Access |
|
|
|
Notes |
; This work was supported by the Research Foundation-Flanders (FWO) and the Concerted Research Action (GOA/14/007). The authors acknowledge Hercules stichting (Projects No. AKUL/13/19 and No. AKUL/13/25). K.H. and S.C. thank the FWO for financial support. T.P. acknowledges the IWT for financial support. S.R., M.V.M., and B.P. acknowledge TOPBOF funding of the University of Antwerp Research Fund. J.W.S. acknowledges Hercules Stichting (Project No. AKUL/13/19). The authors want to thank R. Lieten for help with the XRD measurements and T. Picot for fruitful discussions. The authors gratefully acknowledge R. Ruffer and A. I. Chumakov for fruitful discussions and the European Synchrotron Radiation Facility for the measurement of the SnO<INF>2</INF> powder at the Nuclear Resonance beamline (ID-18). This research used resources of the Advanced Photon Source, a US Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. ; |
Approved |
Most recent IF: 3.836 |
|
|
Call Number |
UA @ lucian @ c:irua:144305 |
Serial |
4667 |
|
Permanent link to this record |
|
|
|
|
Author |
Lozano, D.P.; Couet, S.; Petermann, C.; Hamoir, G.; Jochum, J.K.; Picot, T.; Menendez, E.; Houben, K.; Joly, V.; Antohe, V.A.; Hu, M.Y.; Leu, B.M.; Alatas, A.; Said, A.H.; Roelants, S.; Partoens, B.; Milošević, M.V.; Peeters, F.M.; Piraux, L.; Van de Vondel, J.; Vantomme, A.; Temst, K.; Van Bael, M.J. |
![goto web page (via DOI) doi](http://nano.uantwerpen.be/nanorefs/img/doi.gif)
|
|
Title |
Experimental observation of electron-phonon coupling enhancement in Sn nanowires caused by phonon confinement effects |
Type |
A1 Journal article |
|
Year |
2019 |
Publication |
Physical review B |
Abbreviated Journal |
Phys Rev B |
|
|
Volume |
99 |
Issue |
6 |
Pages |
064512 |
|
|
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
|
|
Abstract |
Reducing the size of a superconductor below its characteristic length scales can either enhance or suppress its critical temperature (T-c). Depending on the bulk value of the electron-phonon coupling strength, electronic and phonon confinement effects will play different roles in the modification of T-c. Experimentally disentangling each contribution has remained a challenge. We have measured both the phonon density of states and T-c of Sn nanowires with diameters of 18, 35, and 100 nm in order to quantify the effects of phonon confinement on superconductivity. We observe a shift of the phonon frequency towards the low-energy region and an increase in the electron-phonon coupling constant that can account for the measured increase in T-c. |
|
|
Address |
|
|
|
Corporate Author |
|
Thesis ![sorted by Thesis field, ascending order (up)](img/sort_asc.gif) |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Wos |
000459322400005 |
Publication Date |
2019-02-21 |
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
2469-9969; 2469-9950 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
3.836 |
Times cited |
11 |
Open Access |
|
|
|
Notes |
; We would like to thanks Jeroen Scheerder and Wout Keijers for their help and assistance during the low-temperature measurements. This work was supported by the Research Foundation Flanders (FWO), the Concerted Research Action (GOA/14/ 007), the Federation Wallonie-Bruxelles (ARC 13/18-052, Supracryst) and the Fonds de la Recherche Scientifique -FNRS under Grant No. T.0006.16. The authors acknowledge Hercules Stichting (Project Nos. AKUL/13/19 and AKUL/13/25). D.P.L. thanks the FWO for financial support. This research used resources of the Advanced Photon Source, a US Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. ; |
Approved |
Most recent IF: 3.836 |
|
|
Call Number |
UA @ admin @ c:irua:158621 |
Serial |
5212 |
|
Permanent link to this record |
|
|
|
|
Author |
Houben, K.; Jochum, J.K.; Lozano, D.P.; Bisht, M.; Menendez, E.; Merkel, D.G.; Ruffer, R.; Chumakov, A., I; Roelants, S.; Partoens, B.; Milošević, M.V.; Peeters, F.M.; Couet, S.; Vantomme, A.; Temst, K.; Van Bael, M.J. |
![goto web page (via DOI) doi](http://nano.uantwerpen.be/nanorefs/img/doi.gif)
|
|
Title |
In situ study of the \alpha-Sn to \beta-Sn phase transition in low-dimensional systems : phonon behavior and thermodynamic properties |
Type |
A1 Journal article |
|
Year |
2019 |
Publication |
Physical review B |
Abbreviated Journal |
Phys Rev B |
|
|
Volume |
100 |
Issue |
7 |
Pages |
075408 |
|
|
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
|
|
Abstract |
The densities of phonon states of thin Sn films on InSb substrates are determined during different stages of the alpha-Sn to beta-Sn phase transition using nuclear inelastic x-ray scattering. The vibrational entropy and internal energy per atom as a function of temperature are obtained by numerical integration of the phonon density of states. The free energy as a function of temperature for the nanoscale samples is compared to the free energy obtained from ab initio calculations of bulk tin in the alpha-Sn and beta-Sn phase. In thin films this phase transition is governed by the interplay between the vibrational behavior of the film (the phase transition is driven by the vibrational entropy) and the stabilizing influence of the substrate (which depends on the film thickness). This brings a deeper understanding of the role of lattice vibrations in the phase transition of nanoscale Sn. |
|
|
Address |
|
|
|
Corporate Author |
|
Thesis ![sorted by Thesis field, ascending order (up)](img/sort_asc.gif) |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Wos |
000478992800005 |
Publication Date |
2019-08-08 |
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
2469-9969; 2469-9950 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
3.836 |
Times cited |
9 |
Open Access |
|
|
|
Notes |
; This work was supported by the Research Foundation Flanders (FWO) and the Concerted Research Action (Grant No. GOA14/007). K.H., S.C., D.P.L., and E.M. wish to thank the FWO for financial support. The authors gratefully acknowledge the European Synchrotron Radiation Facility (ESRF) for the granted beam time and the use of the in situ UHV preparation chamber. The authors thank B. Opperdoes for technical support and T. Peissker and R. Lieten for fruitful discussions. ; |
Approved |
Most recent IF: 3.836 |
|
|
Call Number |
UA @ admin @ c:irua:161836 |
Serial |
5416 |
|
Permanent link to this record |
|
|
|
|
Author |
Devolder, T.; Bultynck, O.; Bouquin, P.; Nguyen, V.D.; Rao, S.; Wan, D.; Sorée, B.; Radu, I.P.; Kar, G.S.; Couet, S. |
![goto web page (via DOI) doi](http://nano.uantwerpen.be/nanorefs/img/doi.gif)
|
|
Title |
Back hopping in spin transfer torque switching of perpendicularly magnetized tunnel junctions |
Type |
A1 Journal article |
|
Year |
2020 |
Publication |
Physical Review B |
Abbreviated Journal |
Phys Rev B |
|
|
Volume |
102 |
Issue |
18 |
Pages |
184406 |
|
|
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
|
|
Abstract |
We analyze the phenomenon of back hopping in spin-torque induced switching of the magnetization in perpendicularly magnetized tunnel junctions. The analysis is based on single-shot time-resolved conductance measurements of the pulse-induced back hopping. Studying several material variants reveals that the back hopping is a feature of the nominally fixed system of the tunnel junction. The back hopping is found to proceed by two sequential switching events that lead to a final state P' of conductance close to-but distinct from-that of the conventional parallel state. The P' state does not exist at remanence. It generally relaxes to the conventional antiparallel state if the current is removed. The P' state involves a switching of the sole spin-polarizing part of the fixed layers. The analysis of literature indicates that back hopping occurs only when the spin-polarizing layer is too weakly coupled to the rest of the fixed system, which justifies a posteriori the mitigation strategies of back hopping that were implemented empirically in spin-transfer-torque magnetic random access memories. |
|
|
Address |
|
|
|
Corporate Author |
|
Thesis ![sorted by Thesis field, ascending order (up)](img/sort_asc.gif) |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Wos |
000587594900005 |
Publication Date |
2020-11-09 |
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
2469-9969; 2469-9950 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
3.7 |
Times cited |
|
Open Access |
|
|
|
Notes |
; This work was supported in part by the IMEC's Industrial Affiliation Program on STT-MRAM device, and in part by the imec IIAP core CMOS and the Beyond CMOS program of Intel Corporation. T. D. and P. B. thank Jonathan Z. Sun for constructive discussions on the BH phenomenon. ; |
Approved |
Most recent IF: 3.7; 2020 IF: 3.836 |
|
|
Call Number |
UA @ admin @ c:irua:173524 |
Serial |
6458 |
|
Permanent link to this record |
|
|
|
|
Author |
Raymenants, E.; Bultynck, O.; Wan, D.; Devolder, T.; Garello, K.; Souriau, L.; Thiam, A.; Tsvetanova, D.; Canvel, Y.; Nikonov, D.E.; Young, I.A.; Heyns, M.; Sorée, B.; Asselberghs, I.; Radu, I.; Couet, S.; Nguyen, V.D. |
![goto web page (via DOI) doi](http://nano.uantwerpen.be/nanorefs/img/doi.gif)
|
|
Title |
Nanoscale domain wall devices with magnetic tunnel junction read and write |
Type |
A1 Journal article |
|
Year |
2021 |
Publication |
Nature Electronics |
Abbreviated Journal |
|
|
|
Volume |
4 |
Issue |
6 |
Pages |
392-398 |
|
|
Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
|
|
Abstract |
The manipulation of fast domain wall motion in magnetic nanostructures could form the basis of novel magnetic memory and logic devices. However, current approaches for reading and writing domain walls require external magnetic fields, or are based on conventional magnetic tunnel junctions (MTJs) that are not compatible with high-speed domain wall motion. Here we report domain wall devices based on perpendicular MTJs that offer electrical read and write, and fast domain wall motion via spin-orbit torque. The devices have a hybrid free layer design that consists of platinum/cobalt (Pt/Co) or a synthetic antiferromagnet (Pt/Co/Ru/Co) into the free layer of conventional MTJs. We show that our devices can achieve good tunnelling magnetoresistance readout and efficient spin-transfer torque writing that is comparable to current magnetic random-access memory technology, as well as domain wall depinning efficiency that is similar to stand-alone materials. We also show that a domain wall conduit based on a synthetic antiferromagnet offers the potential for reliable domain wall motion and faster write speed compared with a device based on Pt/Co. Domain wall devices based on perpendicular magnetic tunnel junctions with a hybrid free layer design can offer electrical read and write, and fast domain wall motion driven via spin-orbit torque. |
|
|
Address |
|
|
|
Corporate Author |
|
Thesis ![sorted by Thesis field, ascending order (up)](img/sort_asc.gif) |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Wos |
000665011500005 |
Publication Date |
2021-06-23 |
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
2520-1131 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
|
Times cited |
|
Open Access |
OpenAccess |
|
|
Notes |
|
Approved |
Most recent IF: NA |
|
|
Call Number |
UA @ admin @ c:irua:179673 |
Serial |
7003 |
|
Permanent link to this record |
|
|
|
|
Author |
Sethu, K.K.V.; Ghosh, S.; Couet, S.; Swerts, J.; Sorée, B.; De Boeck, J.; Kar, G.S.; Garello, K. |
![find record details (via OpenURL) openurl](img/xref.gif)
|
|
Title |
Optimization of tungsten beta-phase window for spin-orbit-torque magnetic random-access memory |
Type |
A1 Journal article |
|
Year |
2021 |
Publication |
Physical Review Applied |
Abbreviated Journal |
Phys Rev Appl |
|
|
Volume |
16 |
Issue |
6 |
Pages |
064009 |
|
|
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
|
|
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. |
|
|
Address |
|
|
|
Corporate Author |
|
Thesis ![sorted by Thesis field, ascending order (up)](img/sort_asc.gif) |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Wos |
000729005800002 |
Publication Date |
2021-12-03 |
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
2331-7019 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
4.808 |
Times cited |
|
Open Access |
Not_Open_Access |
|
|
Notes |
|
Approved |
Most recent IF: 4.808 |
|
|
Call Number |
UA @ admin @ c:irua:184832 |
Serial |
7007 |
|
Permanent link to this record |
|
|
|
|
Author |
Sankaran, K.; Swerts, J.; Carpenter, R.; Couet, S.; Garello, K.; Evans, R.F.L.; Rao, S.; Kim, W.; Kundu, S.; Crotti, D.; Kar, G.S.; Pourtois, G. |
|
|
Title |
Evidence of magnetostrictive effects on STT-MRAM performance by atomistic and spin modeling |
Type |
P1 Proceeding |
|
Year |
2018 |
Publication |
2018 Ieee International Electron Devices Meeting (iedm) |
Abbreviated Journal |
|
|
|
Volume |
|
Issue |
|
Pages |
|
|
|
Keywords |
P1 Proceeding; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
|
|
Abstract |
For the first time, we demonstrate, using an atomistic description of a 30nm diameter spin-transfer-torque magnetic random access memories (STT-MRAM), that the difference in mechanical properties of its sub-nanometer layers induces a high compressive strain in the magnetic tunnel junction (MTJ) and leads to a detrimental magnetostrictive effect. Our model explains the issues met in engineering the electrical and magnetic performances in scaled STT-MRAM devices. The resulting high compressive strain built in the stack, particularly in the MgO tunnel barrier (t-MgO), and its associated non-uniform atomic displacements, impacts on the quality of the MTJ interface and leads to strain relieve mechanisms such as surface roughness and adhesion issues. We illustrate that the strain gradient induced by the different materials and their thicknesses in the stacks has a negative impact on the tunnel magneto-resistance (TMR), on the magnetic nucleation process and on the STT-MRAM performance. |
|
|
Address |
|
|
|
Corporate Author |
|
Thesis ![sorted by Thesis field, ascending order (up)](img/sort_asc.gif) |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Wos |
000459882300147 |
Publication Date |
|
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
978-1-72811-987-8; 978-1-72811-987-8 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
|
Times cited |
|
Open Access |
|
|
|
Notes |
|
Approved |
no |
|
|
Call Number |
UA @ admin @ c:irua:158694 |
Serial |
7942 |
|
Permanent link to this record |
|
|
|
|
Author |
Vermeulen, B.B.; Raymenants, E.; Pham, V.T.; Pizzini, S.; Sorée, B.; Wostyn, K.; Couet, S.; Nguyen, V.D.; Temst, K. |
![goto web page (via DOI) doi](http://nano.uantwerpen.be/nanorefs/img/doi.gif)
|
|
Title |
Towards fully electrically controlled domain-wall logic |
Type |
A1 Journal article |
|
Year |
2024 |
Publication |
AIP advances |
Abbreviated Journal |
|
|
|
Volume |
14 |
Issue |
2 |
Pages |
025030-25035 |
|
|
Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
|
|
Abstract |
Utilizing magnetic tunnel junctions (MTJs) for write/read and fast spin-orbit-torque (SOT)-driven domain-wall (DW) motion for propagation, enables non-volatile logic and majority operations, representing a breakthrough in the implementation of nanoscale DW logic devices. Recently, current-driven DW logic gates have been demonstrated via magnetic imaging, where the Dzyaloshinskii-Moriya interaction (DMI) induces chiral coupling between perpendicular magnetic anisotropy (PMA) regions via an in-plane (IP) oriented region. However, full electrical operation of nanoscale DW logic requires electrical write/read operations and a method to pattern PMA and IP regions compatible with the fabrication of PMA MTJs. Here, we study the use of a Hybrid Free Layer (HFL) concept to combine an MTJ stack with DW motion materials, and He+ ion irradiation to convert the stack from PMA to IP. First, we investigate the free layer thickness dependence of 100-nm diameter HFL-MTJ devices and find an optimal CoFeB thickness, from 7 to 10 angstrom, providing high tunneling magnetoresistance (TMR) readout and efficient spin-transfer torque (STT) writing. We then show that high DMI materials, like Pt/Co, can be integrated into an MTJ stack via interlayer exchange coupling with the CoFeB free layer. In this design, DMI values suitable for SOT-driven DW motion are measured by asymmetric bubble expansion. Finally, we demonstrate that He+ irradiation reliably converts the coupled free layers from PMA to IP. These findings offer a path toward the integration of fully electrically controlled DW logic circuits. |
|
|
Address |
|
|
|
Corporate Author |
|
Thesis ![sorted by Thesis field, ascending order (up)](img/sort_asc.gif) |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Wos |
001163573400005 |
Publication Date |
2024-02-16 |
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
2158-3226 |
ISBN |
|
Additional Links |
UA library record; WoS full record |
|
|
Impact Factor |
|
Times cited |
|
Open Access |
Not_Open_Access |
|
|
Notes |
|
Approved |
Most recent IF: NA |
|
|
Call Number |
UA @ admin @ c:irua:203823 |
Serial |
9109 |
|
Permanent link to this record |
|
|
|
|
Author |
Vermeulen, B.B.; Monteiro, M.G.; Giuliano, D.; Sorée, B.; Couet, S.; Temst, K.; Nguyen, V.D. |
![find record details (via OpenURL) openurl](img/xref.gif)
|
|
Title |
Magnetization-switching dynamics driven by chiral coupling |
Type |
A1 Journal article |
|
Year |
2024 |
Publication |
Physical review applied |
Abbreviated Journal |
|
|
|
Volume |
21 |
Issue |
2 |
Pages |
024050-11 |
|
|
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
|
|
Abstract |
The Dzyaloshinskii-Moriya interaction (DMI) is known to play a central role in stabilizing chiral spin textures such as skyrmions and domain walls (DWs). Electrical manipulation of DW and skyrmion motion offers possibilities for next-generation, scalable and energy-efficient spintronic devices. However, achieving the full potential of these nanoscale devices requires overcoming several challenges, including reliable electrical write and read techniques for these magnetic objects, and addressing pinning and Joule-heating concerns. Here, through micromagnetic simulations and analytical modeling, we show that DMI can directly induce magnetization switching of a nanomagnet with perpendicular magnetic anisotropy (PMA). We find that the switching is driven by the interplay between the DMI-induced magnetic frustration and the PMA. By introducing magnetic tunnel junctions to electrically access and control the magnetization direction of the PMA nanomagnet, we first show the potential of this concept to enable high-density fieldfree spin-orbit torque magnetic random-access memory. Ultimately, we demonstrate that it offers a way of transferring and processing spin information for logic operation without relying on current-driven DW or skyrmion motion. |
|
|
Address |
|
|
|
Corporate Author |
|
Thesis ![sorted by Thesis field, ascending order (up)](img/sort_asc.gif) |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Wos |
001187487900001 |
Publication Date |
2024-02-26 |
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
2331-7019 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
4.6 |
Times cited |
|
Open Access |
|
|
|
Notes |
|
Approved |
Most recent IF: 4.6; 2024 IF: 4.808 |
|
|
Call Number |
UA @ admin @ c:irua:205518 |
Serial |
9157 |
|
Permanent link to this record |
|
|
|
|
Author |
Sethu, K.K.V.; Yasin, F.; Swerts, J.; Sorée, B.; De Boeck, J.; Kar, G.S.; Garello, K.; Couet, S. |
![goto web page (via DOI) doi](http://nano.uantwerpen.be/nanorefs/img/doi.gif)
|
|
Title |
Spin-orbit torque vector quantification in nanoscale magnetic tunnel junctions |
Type |
A1 Journal article |
|
Year |
2024 |
Publication |
ACS nano |
Abbreviated Journal |
|
|
|
Volume |
18 |
Issue |
21 |
Pages |
13506-13516 |
|
|
Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
|
|
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. |
|
|
Address |
|
|
|
Corporate Author |
|
Thesis ![sorted by Thesis field, ascending order (up)](img/sort_asc.gif) |
|
|
|
Publisher |
|
Place of Publication |
|
Editor |
|
|
|
Language |
|
Wos |
001226121700001 |
Publication Date |
2024-05-15 |
|
|
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
|
Series Volume |
|
Series Issue |
|
Edition |
|
|
|
ISSN |
1936-0851 |
ISBN |
|
Additional Links |
UA library record; WoS full record |
|
|
Impact Factor |
17.1 |
Times cited |
|
Open Access |
|
|
|
Notes |
|
Approved |
Most recent IF: 17.1; 2024 IF: 13.942 |
|
|
Call Number |
UA @ admin @ c:irua:205980 |
Serial |
9173 |
|
Permanent link to this record |