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505 results on '"Sjöström, Lars"'

1. Energy-efficient field-free unconventional spin-orbit torque magnetization switching dynamics in van der Waals heterostructures

Author

Pandey, Lalit, Zhao, Bing, Ngaloy, Roselle, Bangar, Himanshu, Ali, Aya, Abdel-Hafiez, Mahmoud, Zhang, Gaojie, Wu, Hao, Chang, Haixin, Sjöström, Lars, Rout, Prasanna, and Dash, Saroj P.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science, Physics - Applied Physics
Abstract

The van der Waals (vdW) heterostructure of emerging two-dimensional (2D) quantum materials, with control over their quantum geometries, crystal symmetries, spin-orbit coupling, and magnetic anisotropies, provides a new platform for generating unconventional nonlinear Hall effects, spin polarization and efficiently controlling the magnetization dynamics for non-volatile spin-based computing. However, so far, the generation of a large out-of-plane spin polarization is limited to achieve energy-efficient field-free magnetization switching and spin dynamics measurements in all-2D vdW heterostructure are so far missing, where the interplay between spins and magnetization dynamics should enable the design of ultrafast spintronic devices. Here, we demonstrate magnetization dynamics and energy-efficient field-free spin-orbit torque (SOT) switching of out-of-plane magnet Fe3GaTe2 due to unconventional Berry curvature-induced out-of-plane spin polarization from a topological Weyl semimetal TaIrTe4 in a vdW heterostructure at room temperature. We observed a large non-linear 2nd harmonic Hall signal at room temperature and evaluated the SOT-induced magnetization dynamics with a large damping-like torque. Deterministic field-free SOT magnetization switching in vdW heterostructure of TaIrTe4/Fe3GaTe2 is observed at room temperature with a low current and power density, which is an order of magnitude better than that of conventional systems. From the magnetization switching experiments, a large SOT efficiency and a very large spin Hall conductivity. These findings on all-vdW heterostructures offer a promising route to energy-efficient and external field-free ultrafast spintronic technologies.

Published
2024

2. Room temperature nonlocal detection of charge-spin interconversion in a topological insulator

Author

Hoque, Anamul Md., Sjöström, Lars, Khokhriakov, Dmitrii, Zhao, Bing, and Dash, Saroj P.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Topological insulators (TIs) are emerging materials for next-generation low-power nanoelectronic and spintronic device applications. TIs possess non-trivial spin-momentum locking features in the topological surface states in addition to the spin-Hall effect (SHE), and Rashba states due to high spin-orbit coupling (SOC) properties. These phenomena are vital for observing the charge-spin conversion (CSC) processes for spin-based memory, logic and quantum technologies. Although CSC has been observed in TIs by potentiometric measurements, reliable nonlocal detection has so far been limited to cryogenic temperatures up to T = 15 K. Here, we report nonlocal detection of CSC and its inverse effect in the TI compound Bi1.5Sb0.5Te1.7Se1.3 at room temperature using a van der Waals heterostructure with a graphene spin-valve device. The lateral nonlocal device design with graphene allows observation of both spin-switch and Hanle spin precession signals for generation, injection and detection of spin currents by the TI. Detailed bias- and gate-dependent measurements in different geometries prove the robustness of the CSC effects in the TI. These findings demonstrate the possibility of using topological materials to make all-electrical room-temperature spintronic devices., Comment: 12 pages, 4 figures

Published
2024
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3. Strong in-plane magnetic anisotropy (Co0.15Fe0.85)5GeTe2/graphene van der Waals heterostructure spin-valve at room temperature

Author

Ngaloy, Roselle, Zhao, Bing, Ershadrad, Soheil, Gupta, Rahul, Davoudiniya, Masoumeh, Bainsla, Lakhan, Sjöström, Lars, Hoque, Anamul M., Kalaboukhov, Alexei, Svedlindh, Peter, Sanyal, Biplab, and Dash, Saroj P.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science, Condensed Matter - Other Condensed Matter, Physics - Applied Physics
Abstract

Van der Waals (vdW) magnets are promising owing to their tunable magnetic properties with doping or alloy composition, where the strength of magnetic interactions, their symmetry, and magnetic anisotropy can be tuned according to the desired application. However, most of the vdW magnet based spintronic devices are so far limited to cryogenic temperatures with magnetic anisotropies favouring out-of-plane or canted orientation of the magnetization. Here, we report room-temperature lateral spin-valve devices with strong in-plane magnetic anisotropy of the vdW ferromagnet (Co0.15Fe0.85)5GeTe2 (CFGT) in heterostructures with graphene. Magnetization measurements reveal above room-temperature ferromagnetism in CFGT with a strong in-plane magnetic anisotropy. Density functional theory calculations show that the magnitude of the anisotropy depends on the Co concentration and is caused by the substitution of Co in the outermost Fe layer. Heterostructures consisting of CFGT nanolayers and graphene were used to experimentally realize basic building blocks for spin valve devices such as efficient spin injection and detection. The spin transport and Hanle spin precession measurements prove a strong in-plane and negative spin polarization at the interface with graphene, which is supported by the calculated spin-polarized density of states of CFGT. The in-plane magnetization of CFGT at room temperature proves its usefulness in graphene lateral spin-valve devices, thus opening further opportunities for spintronic technologies.

Published
2023

4. Large out-of-plane spin-orbit torque in topological Weyl semimetal candidate TaIrTe4

Author

Bainsla, Lakhan, Zhao, Bing, Hoque, Anamul Md., Sjöström, Lars, Behera, Nilamani, Abdel-Hafiez, Mahmoud, Åkerman, Johan, and Dash, Saroj P.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Topological quantum materials, with novel spin textures and broken crystal symmetries are suitable candidates for spintronic memory technologies. Their unique electronic properties, such as protected surface states and exotic quasiparticles, can provide an out-of-plane spin polarized current needed for external field free magnetization switching of magnets with perpendicular magnetic anisotropy. Conventional spin-orbit torque materials, such as heavy metals and topological insulators, provide only an in-plane spin polarized current, and recently explored materials with lower crystal symmetries provide very low out-of-plane spin polarized current components, which is not suitable for energy-efficient spin-orbit torque (SOT) applications. Here, we demonstrate a large out-of-plane damping-like SOT at room temperature using a topological Weyl semimetal candidate TaIrTe4 with a lower crystal symmetry. We performed spin-orbit torque ferromagnetic resonance (STFMR) experiments in a TaIrTe4/Ni80Fe20 heterostructure and observed a large out-of-plane damping-like SOT efficiency. The out-of-plane spin Hall conductivity is estimated to be an order of magnitude higher than the reported values in other materials. These findings of high spin Hall conductivity and large out-of-plane SOT efficiency are suitable for the development of energy efficient and external field-free spintronic devices.

Published
2023

6. Strong In-Plane Magnetization and Spin Polarization in (Co0.15Fe0.85)5GeTe2/Graphen e van der Waals Heterostructure Spin-Valve at Room Temperature

Author

Ngaloy, Roselle, Zhao, Bing, Ershadrad, Soheil, Gupta, Rahul, Davoudiniya, Masoumeh, Bainsla, Lakhan, Sjöström, Lars, Hoque, Md. Anamul, Kalaboukhov, Alexei, Svedlindh, Peter, Sanyal, Biplab, Dash, Saroj Prasad, Ngaloy, Roselle, Zhao, Bing, Ershadrad, Soheil, Gupta, Rahul, Davoudiniya, Masoumeh, Bainsla, Lakhan, Sjöström, Lars, Hoque, Md. Anamul, Kalaboukhov, Alexei, Svedlindh, Peter, Sanyal, Biplab, and Dash, Saroj Prasad

Abstract

Van der Waals (vdW) magnets are promising, because of their tunable magnetic properties with doping or alloy composition, where the strength of magnetic interactions, their symmetry, and magnetic anisotropy can be tuned according to the desired application. However, so far, most of the vdW magnet-based spintronic devices have been limited to cryogenic temperatures with magnetic anisotropies favoring out-of-plane or canted orientation of the magnetization. Here, we report beyond room-temperature lateral spin-valve devices with strong in-plane magnetization and spin polarization of the vdW ferromagnet (Co0.15Fe0.85)5GeTe2 (CFGT) in heterostructures with graphene. Density functional theory (DFT) calculations show that the magnitude of the anisotropy depends on the Co concentration and is caused by the substitution of Co in the outermost Fe layer. Magnetization measurements reveal the above room-temperature ferromagnetism in CFGT and clear remanence at room temperature. Heterostructures consisting of CFGT nanolayers and graphene were used to experimentally realize basic building blocks for spin valve devices, such as efficient spin injection and detection. Further analysis of spin transport and Hanle spin precession measurements reveals a strong in-plane magnetization with negative spin polarization at the interface with graphene, which is supported by the calculated spin-polarized density of states of CFGT. The in-plane magnetization of CFGT at room temperature proves its usefulness in graphene lateral spin-valve devices, thus revealing its potential application in spintronic technologies.

Published
2024
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7. Strong In-Plane Magnetization and Spin Polarization in (Co0.15Fe0.85)5GeTe2/Graphene van der Waals Heterostructure Spin-Valve at Room Temperature

Author

Ngaloy, Roselle, primary, Zhao, Bing, additional, Ershadrad, Soheil, additional, Gupta, Rahul, additional, Davoudiniya, Masoumeh, additional, Bainsla, Lakhan, additional, Sjöström, Lars, additional, Hoque, Md. Anamul, additional, Kalaboukhov, Alexei, additional, Svedlindh, Peter, additional, Sanyal, Biplab, additional, and Dash, Saroj Prasad, additional

Published
2024
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8. Large out-of-plane spin–orbit torque in topological Weyl semimetal TaIrTe4.

Author

Bainsla, Lakhan, Zhao, Bing, Behera, Nilamani, Hoque, Anamul Md., Sjöström, Lars, Martinelli, Anna, Abdel-Hafiez, Mahmoud, Åkerman, Johan, and Dash, Saroj P.

Subjects
SPIN-polarized currents, PERPENDICULAR magnetic anisotropy, CRYSTAL symmetry, TORQUE, FERROMAGNETIC resonance
Abstract

The unique electronic properties of topological quantum materials, such as protected surface states and exotic quasiparticles, can provide an out-of-plane spin-polarized current needed for external field-free magnetization switching of magnets with perpendicular magnetic anisotropy. Conventional spin–orbit torque (SOT) materials provide only an in-plane spin-polarized current, and recently explored materials with lower crystal symmetries provide very low out-of-plane spin-polarized current components, which are not suitable for energy-efficient SOT applications. Here, we demonstrate a large out-of-plane damping-like SOT at room temperature using the topological Weyl semimetal candidate TaIrTe4 with a lower crystal symmetry. We performed spin–torque ferromagnetic resonance (STFMR) and second harmonic Hall measurements on devices based on TaIrTe4/Ni80Fe20 heterostructures and observed a large out-of-plane damping-like SOT efficiency. The out-of-plane spin Hall conductivity is estimated to be (4.05 ± 0.23)×104 (ℏ ⁄ 2e) (Ωm)−1, which is an order of magnitude higher than the reported values in other materials. Topological semimetals offer the potential for new-generation spintronic devices. Here, the authors demonstrate a large out-of-plane damping-like spin–orbit torque efficiency in a heterostructure based on the Weyl semimetal TaIrTe4. [ABSTRACT FROM AUTHOR]

Published
2024
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10. Room temperature nonlocal detection of charge-spin interconversion in a topological insulator.

Author

Hoque, Md. Anamul, Sjöström, Lars, Khokhriakov, Dmitrii, Zhao, Bing, and Dash, Saroj Prasad

Subjects
TOPOLOGICAL insulators, SPIN-orbit interactions, QUANTUM logic, SPINTRONICS, SEMIMETALS, SURFACE states
Abstract

Topological insulators (TIs) are emerging materials for next-generation low-power nanoelectronic and spintronic device applications. TIs possess non-trivial spin-momentum locking features in the topological surface states in addition to the spin-Hall effect (SHE), and Rashba states due to high spin-orbit coupling (SOC) properties. These phenomena are vital for observing the charge-spin conversion (CSC) processes for spin-based memory, logic and quantum technologies. Although CSC has been observed in TIs by potentiometric measurements, reliable nonlocal detection has so far been limited to cryogenic temperatures up to T = 15 K. Here, we report nonlocal detection of CSC and its inverse effect in the TI compound Bi1.5Sb0.5Te1.7Se1.3 at room temperature using a van der Waals heterostructure with a graphene spin-valve device. The lateral nonlocal device design with graphene allows observation of both spin-switch and Hanle spin precession signals for generation, injection and detection of spin currents by the TI. Detailed bias- and gate-dependent measurements in different geometries prove the robustness of the CSC effects in the TI. These findings demonstrate the possibility of using topological materials to make all-electrical room-temperature spintronic devices. [ABSTRACT FROM AUTHOR]

Published
2024
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16. Hormones, Body Composition and Cardiovascular Risk

Author

Sjöström, Lars, Alpsten, Magne, Andersson, Björn, Bengtsson, Bengt-Åke, Bengtsson, Calle, Björntorp, Per, Bosaeus, Ingvar, Brummer, Robert Jan, Chowdhury, Badrul, Edén, Staffan, Ernest, Ingrid, Holmäng, Sten, Isaksson, Olle, Kvist, Henry, Lapidus, Leif, Larsson, Bo, Lindstedt, Göran, Lindstedt, Sven, Lissner, Lauren, Lönn, Lars, Mårin, Per, Stenlöf, Kaj, Tölli, Jukka, Chu, Ernest H. Y., editor, Ellis, Kenneth J., editor, and Eastman, Jerry D., editor

Published
1993
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17. Transmembrane 6 superfamily member 2 gene variant disentangles nonalcoholic steatohepatitis from cardiovascular disease

Author

Dongiovanni, Paola, Petta, Salvatore, Maglio, Cristina, Fracanzani, Anna Ludovica, Pipitone, Rosaria, Mozzi, Enrico, Motta, Benedetta Maria, Kaminska, Dorota, Rametta, Raffaela, Grimaudo, Stefania, Pelusi, Serena, Montalcini, Tiziana, Alisi, Anna, Maggioni, Marco, Kärjä, Vesa, Borén, Jan, Käkelä, Pirjo, Di Marco, Vito, Xing, Chao, Nobili, Valerio, Dallapiccola, Bruno, Craxi, Antonio, Pihlajamäki, Jussi, Fargion, Silvia, Sjöström, Lars, Carlsson, Lena M., Romeo, Stefano, and Valenti, Luca

Published
2015
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18. Effects of bariatric surgery on cancer incidence in obese patients in Sweden (Swedish Obese Subjects Study): a prospective, controlled intervention trial

Author

Sjöström, Lars, Gummesson, Anders, Sjöström, C David, Narbro, Kristina, Peltonen, Markku, Wedel, Hans, Bengtsson, Calle, Bouchard, Claude, Carlsson, Björn, Dahlgren, Sven, Jacobson, Peter, Karason, Kristjan, Karlsson, Jan, Larsson, Bo, Lindroos, Anna-Karin, Lönroth, Hans, Näslund, Ingmar, Olbers, Torsten, Stenlöf, Kaj, Torgerson, Jarl, and Carlsson, Lena MS

Published
2009
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21. Association of Bariatric Surgery With Long-term Remission of Type 2 Diabetes and With Microvascular and Macrovascular Complications

Author

Sjöström, Lars, Peltonen, Markku, Jacobson, Peter, Ahlin, Sofie, Andersson-Assarsson, Johanna, Anveden, Åsa, Bouchard, Claude, Carlsson, Björn, Karason, Kristjan, Lönroth, Hans, Näslund, Ingmar, Sjöström, Elisabeth, Taube, Magdalena, Wedel, Hans, Svensson, Per-Arne, Sjöholm, Kajsa, and Carlsson, Lena M. S.

Published
2014
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25. The IRS1 rs2943641 Variant and Risk of Future Cancer Among Morbidly Obese Individuals

Author

Maglio, Cristina, Ericson, Ulrika, Burza, Maria Antonella, Mancina, Rosellina Margherita, Pirazzi, Carlo, Assarsson, Johanna Andersson, Sjöholm, Kajsa, Baroni, Marco Giorgio, Svensson, Per-Arne, Montalcini, Tiziana, Pujia, Arturo, Sjöström, Lars, Wiklund, Olov, Carlsson, Lena M. S., Borén, Jan, Orho-Melander, Marju, and Romeo, Stefano

Published
2013

34. Novel association approach for variable number tandem repeats (VNTRs) identifies DOCK5 as a susceptibility gene for severe obesity

Author

El-Sayed Moustafa, Julia S., Eleftherohorinou, Hariklia, de Smith, Adam J., Andersson-Assarsson, Johanna C., Couto Alves, Alexessander, Hadjigeorgiou, Eleni, Walters, Robin G., Asher, Julian E., Bottolo, Leonardo, Buxton, Jessica L., Sladek, Rob, Meyre, David, Dina, Christian, Visvikis-Siest, Sophie, Jacobson, Peter, Sjöström, Lars, Carlsson, Lena M.S., Walley, Andrew, Falchi, Mario, Froguel, Philippe, Blakemore, Alexandra I.F., and Coin, Lachlan J.M.

Published
2012
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36. Low-Frequency Variants in HMGA1 Are Not Associated With Type 2 Diabetes Risk

Author

Marquez, Marcel, Huyvaert, Marlène, Perry, John R.B., Pearson, Richard D., Falchi, Mario, Morris, Andrew P., Vivequin, Sidonie, Lobbens, Stéphane, Yengo, Loïc, Gaget, Stefan, Pattou, Francois, Poulain-Godefroy, Odile, Charpentier, Guillaume, Carlsson, Lena M.S., Jacobson, Peter, Sjöström, Lars, Lantieri, Olivier, Heude, Barbara, Walley, Andrew, Balkau, Beverley, Marre, Michel, Froguel, Philippe, and Cauchi, Stéphane

Published
2012
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37. Bariatric Surgery and Long-term Cardiovascular Events

Author

Sjöström, Lars, Peltonen, Markku, Jacobson, Peter, Sjöström, C. David, Karason, Kristjan, Wedel, Hans, Ahlin, Sofie, Anveden, Åsa, Bengtsson, Calle, Bergmark, Gerd, Bouchard, Claude, Carlsson, Björn, Dahlgren, Sven, Karlsson, Jan, Lindroos, Anna-Karin, Lönroth, Hans, Narbro, Kristina, Näslund, Ingmar, Olbers, Torsten, Svensson, Per-Arne, and Carlsson, Lena M.

Published
2012
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40. Nonsurgical Weight Loss for Extreme Obesity in Primary Care Settings: Results of the Louisiana Obese Subjects Study

Author

Ryan, Donna H., Johnson, William D., Myers, Valerie H., Prather, Tiffany L., McGlone, Meghan M., Rood, Jennifer, Brantley, Phillip J., Bray, George A., Gupta, Alok K., Broussard, Alan P., Barootes, Bryan G., Elkins, Brian L., Gaudin, David E., Savory, Robert L., Brock, Ricky D., Datz, Geralyn, Pothakamuri, Srininvasa R., McKnight, G. Tipton, Stenlof, Kaj, and Sjöström, Lars V.

Published
2010

43. Differences in age at breeding between two genetically different populations of brown trout (Salmo trutta)

Author

Sjöström, Lars

Subjects
Ecology, Population genetics, Cox Proportional Hazards model, Complementary Log-Log Link model, Evolutionary biology, Sannolikhetsteori och statistik, Biodiversity, Survival analysis, Probability Theory and Statistics, Accelerated Failure-Time model
Abstract

Survival analysis is an effective tool for conservation studies, since it measure the risk of an event that is important for the survival of populations and preservation of biodiversity. In this thesis three different models for survival analysis are used to estimate the age at breeding between two genetically different populations of brown trout. These populations are an evolutionary enigma, since they apparently coexist in direct competition with each other, which according to ecological theory should not happen. Thus it is of interest if differences between them can be identified. The data consists of brown trouts and has been collected over 20 years. The models are the Cox Proportional Hazards model, the Complementary Log-Log Link model and the Log Logistic Accelerated Failure-Time model. The Cox model were estimated in three different ways due to the nonproportional hazards in the estimates of time to breeding, which gave different interpretations of the same model. All of the models agree that the population B breed at younger ages than the population A, which suggests that the two populations have different reproductive strategies.

Published
2019

47. Villkorlig körkortsåterkallelse med ISA vid hastighetsöverträdelse

Author

Jonsson, Tomas, Sjöström, Lars Olov, Jonsson, Tomas, and Sjöström, Lars Olov

Abstract

Rapporten är framtagen med ekonomiska bidrag från Trafikverket, Skyltfonden. Ståndpunkter och slutsatser i rapporten reflekterar författaren och överensstämmer inte med nödvändighet med Trafikverkets ståndpunkter och slutsatser inom rapportens ämnesområden. Syftet med projektet har varit att genomföra en förstudie för att kartlägga intresset för ett införande dels från förarna som riskerar indragning av körkort, dels från politiker. Undersökningen i den sistnämnda gruppen har riktats till ledamöter i riksdagens trafikutskott. För att uppnå projektets syfte har vi gjort en litteraturstudie för att kunna redovisa en översikt av erfarenheter av försök med ISA, både i Sverige och internationellt. Litteraturstudien har använts för att i rapporten kunna teckna en bakgrund till ISA-utvecklingen fram till idag och dess möjligheter i det fortsatta trafiksäkerhetsarbetet. Vidare har vi genomfört två olika enkätstudier, den ena med personer som fått körkortet återkallat på grund av hastighetsöverträdelse och den andra med ledamöter i riksdagens trafikutskott. Resultaten av litteraturstudien och enkätstudierna redovisas i denna rapport. Litteraturstudien visar att de erfarenheter som har gjorts fram till idag är att användning av ISA har en potential att påverka förares körbeteende så att hastighetsefterlevnaden och därmed trafiksäkerheten förbättras. Resultaten från de svenska fältförsöken med ISA 1999-2002 visar t.ex. att de förväntade positiva effekterna uppnåddes och faktiskt också överträffades. I försöken uppnåddes bättre trafiksäkerhet utan att för den skull den genomsnittliga restiden förlängdes. Likaså uppvisar försöksprojektet Grönt ljus där MHF var en av aktörerna uppnåddes tydligt positiva resultat på körvanorna enligt de utvärderingar som gjordes. Idag har flera försäkringsbolag infört försäkringslösningar som med ISA som verktyg premierar god hastighetsefterlevnad. Internationella försök i andra europeiska länder indikerar också att användning av ISA-teknik kan va

Published
2019

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