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Publications (10 of 631) Show all publications
Sousa, O. M., Sorgenfrei, F., Carvalho, F. O., Assali, L. V., Lalic, M. V., Thunström, P., . . . Klautau, A. B. (2025). Ab initio investigation of ZnV2O4, ZnV2S4, and ZnV2Se4 as cathode materials for aqueous zinc-ion batteries. Acta Materialia, 282, Article ID 120468.
Open this publication in new window or tab >>Ab initio investigation of ZnV2O4, ZnV2S4, and ZnV2Se4 as cathode materials for aqueous zinc-ion batteries
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2025 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 282, article id 120468Article in journal (Refereed) Published
Abstract [en]

Zinc-ion batteries (ZIBs) employing aqueous electrolytes have emerged as one of the most promising alternatives to lithium-ion batteries (LIBs). Nonetheless, the development of ZIBs is hindered by the scarcity of cathode materials with suitable electrochemical properties. In this work, we investigate the unique properties of zinc vanadate oxide (ZnV2O4, ZVO) and zinc vanadate sulfide (ZnV2S4, ZVS) compounds as cathode materials, focusing on their crystal structures, electrochemical performance, spectroscopic features and potential applications in ZIBs. Additionally, we investigate a new cathode material, zinc vanadate selenide (ZnV2Se4, ZVSe), constructed by replacing sulfur with selenium in the ZVS cubic structure. Our findings reveal that these compounds exhibit distinct electronic and electrochemical properties, although they have similar magnetic properties due to the fact that vanadium has the same oxidation state in all three compounds. On average, ZVS stands out as the most promising candidate for ZIBs cathodes, followed by ZVO. ZVSe, shows lower electrochemical performance and also has the obvious drawback of being more costly than the sulfur- and oxygen-based compounds. Our theoretical results align closely with available experimental data, both for electrochemical properties as well as x-ray and photoelectron spectroscopy, where a comparison can be made.

Place, publisher, year, edition, pages
Elsevier, 2025
Keywords
Cathode materials, density functional theory, Zinc-ion batteries, ZnV2O4, ZnV2S4
National Category
Materials Chemistry Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-542788 (URN)10.1016/j.actamat.2024.120468 (DOI)001344055100001 ()
Funder
Knut and Alice Wallenberg FoundationSwedish Research CouncilEU, European Research Council, 854843-FASTCORRStandUpeSSENCE - An eScience CollaborationNational Academic Infrastructure for Supercomputing in Sweden (NAISS)
Available from: 2024-11-15 Created: 2024-11-15 Last updated: 2024-11-15Bibliographically approved
Xu, Q., Shen, Z., Edstroem, A., Miranda, I. P., Lu, Z., Bergman, A., . . . Delin, A. (2025). Design of 2D skyrmionic metamaterials through controlled assembly. npj Computational Materials, 11(1), Article ID 56.
Open this publication in new window or tab >>Design of 2D skyrmionic metamaterials through controlled assembly
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2025 (English)In: npj Computational Materials, E-ISSN 2057-3960, Vol. 11, no 1, article id 56Article in journal (Refereed) Published
Abstract [en]

Despite extensive research on magnetic skyrmions and antiskyrmions, a significant challenge remains in crafting nontrivial high-order skyrmionic textures with varying, or even tailor-made, topologies. We address this challenge, by focusing on a construction pathway of skyrmionic metamaterials within a monolayer thin film and suggest several skyrmionic metamaterials that are surprisingly stable, i.e., long-lived, due to a self-stabilization mechanism. This makes these new textures promising for applications. Central to our approach is the concept of 'simulated controlled assembly', in short, a protocol inspired by 'click chemistry' that allows for positioning topological magnetic structures where one likes, and then allowing for energy minimization to elucidate the stability. Utilizing high-throughput atomistic-spin-dynamic simulations alongside state-of-the-art AI-driven tools, we have isolated skyrmions (topological charge Q = 1), antiskyrmions (Q = - 1), and skyrmionium (Q = 0). These entities serve as foundational 'skyrmionic building blocks' to form the here-reported intricate textures. In this work, two key contributions are introduced to the field of skyrmionic systems. First, we present a novel combination of atomistic spin dynamics simulations and controlled assembly protocols for the stabilization and investigation of new topological magnets. Second, using the aforementioned methods we report on the discovery of skyrmionic metamaterials.

Place, publisher, year, edition, pages
NATURE PORTFOLIO, 2025
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-552423 (URN)10.1038/s41524-025-01534-4 (DOI)001435385600001 ()2-s2.0-85219636762 (Scopus ID)
Funder
Swedish Research Council, 2023-04239Knut and Alice Wallenberg FoundationKnut and Alice Wallenberg FoundationSwedish Research Council, 2022-06725Swedish Research Council, 2018-05973Swedish Research CouncilSwedish Research Council
Available from: 2025-03-17 Created: 2025-03-17 Last updated: 2025-03-17Bibliographically approved
Hasan, M. N., Salehi, N., Sorgenfrei, F., Delin, A., Di Marco, I., Bergman, A., . . . Karmakar, D. (2025). Dynamical electronic correlations and chiral magnetism in the van der Waals magnet Fe4GeTe2. Physical Review B, 111(13), Article ID 134449.
Open this publication in new window or tab >>Dynamical electronic correlations and chiral magnetism in the van der Waals magnet Fe4GeTe2
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2025 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 111, no 13, article id 134449Article in journal (Refereed) Published
Abstract [en]

Among the quasi-two-dimensional van der Waals magnetic systems, Fe4GeTe2 makes a profound impact due to its near-room-temperature ferromagnetic behavior and the complex magnetothermal phase diagram exhibiting multiple phase transformations, as observed from magnetization and magnetotransport measurements. A complete analysis of these phase transformations in light of electronic correlation and its impact on the underlying magnetic interactions remain unexplored in the existing literature. Using first-principles methodologies, incorporating the dynamical nature of electron correlation, we have analyzed the interplay of the direction of magnetization in an easy-plane and easy-axis manner with the underlying crystal symmetry, which reveals the opening of a pseudogap feature beyond the spin-reorientation transition temperature. The impact of dynamical correlation on the calculated magnetic circular dichroism and x-ray absorption spectrum of the L-edge of Fe atoms compare well with existing experimental observations. The calculated intersite Heisenberg exchange interactions display a complicated nature, depending upon the pairwise interactions among the two inequivalent Fe sites, indicating a Ruderman-Kittel-Kasuya-Yosida-like behavior of the magnetic interactions. We note the existence of significant anisotropic and antisymmetric exchange interactions, resulting in a chirality in the magnetic behavior of the system. Subsequent investigation of the dynamical aspects of magnetism in Fe4GeTe2 and the respective magnetothermal phase diagram reveals that the dynamical nature of spins and the decoupling of the magnetic properties for both sites of Fe is crucial to explain all the experimentally observed phase transformations.

Place, publisher, year, edition, pages
American Physical Society, 2025
National Category
Condensed Matter Physics Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-557131 (URN)10.1103/PhysRevB.111.134449 (DOI)001487642000005 ()2-s2.0-105004256524 (Scopus ID)
Funder
EU, European Research Council
Available from: 2025-05-27 Created: 2025-05-27 Last updated: 2025-05-27Bibliographically approved
Elhanoty, M. F., Eriksson, O., Ong, C. S. & Grånäs, O. (2025). How quantum selection rules influence the magneto-optical effects of driven ultrafast magnetization dynamics. Physical Review B, 111(14), Article ID 144410.
Open this publication in new window or tab >>How quantum selection rules influence the magneto-optical effects of driven ultrafast magnetization dynamics
2025 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 111, no 14, article id 144410Article in journal (Refereed) Published
Abstract [en]

Ultrafast magnetization dynamics driven by ultrashort pump lasers is typically explained by changes in the electronic populations and scattering pathways of excited conduction electrons. This conventional approach overlooks the fundamental role of quantum mechanical selection rules, governing transitions from the core states to the conduction band, that form the key method of the probing step in these experiments. By employing fully ab initio time-dependent density functional theory, we reveal that these selection rules profoundly influence the interpretation of ultrafast spin dynamics at specific probe energies. Our analysis for hcp Co and fcc Ni at the M edge demonstrates that the transient dynamics, as revealed in pump-probe experiments, arises from a complex interplay of optical excitations of the M shell. Taking into account the selection rules and conduction electron spin flips leads to highly energy-dependent dynamics. These findings address long-standing discrepancies in experimental transverse magneto-optical Kerr effect measurements and show that only through meticulous consideration of the matrix elements at the probe stage, can one ensure that the magnetization dynamics is revealed in its true nature, instead of being muddled by artifacts arising from the choice of probe energy.

Place, publisher, year, edition, pages
American Physical Society, 2025
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-555796 (URN)10.1103/PhysRevB.111.144410 (DOI)001468563500002 ()2-s2.0-105002740796 (Scopus ID)
Funder
Swedish Research Council, 2019-03901EU, European Research Council, 854843EU, European Research Council, 854843StandUpKnut and Alice Wallenberg FoundationSwedish Research Council, 2018-05973Swedish Research Council, 2022-06725
Available from: 2025-05-13 Created: 2025-05-13 Last updated: 2025-05-13Bibliographically approved
Huang, S., Dastanpour, E., Ström, V., Varga, L. K., Eriksson, O., Jin, H. & Vitos, L. (2025). Lattice and spin entropy changes in B2-type magnetocaloric Al-Mn-Ni alloy. Journal of Physics D: Applied Physics, 58(7), Article ID 075001.
Open this publication in new window or tab >>Lattice and spin entropy changes in B2-type magnetocaloric Al-Mn-Ni alloy
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2025 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 58, no 7, article id 075001Article in journal (Refereed) Published
Abstract [en]

Understanding the electronic, lattice, and magnetic contributions to the magnetocaloric effect in magnetic materials can help to elucidate and optimize their performance. In this work, the structural and magnetocaloric properties of Al–Mn–Ni alloy are experimentally determined and theoretically analyzed based on ab initio calculations. The dominating B2 phase associated with the Mn-rich sublattice is found to be responsible for the observed magnetocaloric properties. The magnetic entropy change, refrigerant capacity, and adiabatic temperature change are evaluated. Through the analysis of the data, we find that for the B2 phase, changing from ferromagnetic to paramagnetic configurations results in a pronounced elastic hardening despite the volume expansion. The decrease in lattice entropy is significant and contributes negatively to the magnetic and electronic entropy changes. Our work emphasizes the critical role of the lattice sector in the magnetocaloric effect, and provides an in-depth understanding of the individual entropy terms in magnetic solid solutions.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2025
Keywords
magnetocaloric effect, lattice entropy, magnetic entropy, B2 structure, ab-initio calculations
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-545744 (URN)10.1088/1361-6463/ad9591 (DOI)001374000600001 ()
Funder
Swedish Research Council, 2017-06474Swedish Research Council, 2019-04971Swedish Research Council, 2022-04758Vinnova, 2019-05111Swedish Energy AgencyStandUpSwedish Research Council, 2018-05973Swedish Foundation for Strategic ResearchWallenberg FoundationseSSENCE - An eScience CollaborationCarl Tryggers foundation , 19:325Carl Tryggers foundation , 20:474Swedish National Infrastructure for Computing (SNIC)
Available from: 2024-12-20 Created: 2024-12-20 Last updated: 2024-12-20Bibliographically approved
Simak, S. I., Delczeg-Czirjak, E. K. & Eriksson, O. (2025). Machine learning for improved density functional theory thermodynamics. Scientific Reports, 15(1), Article ID 17212.
Open this publication in new window or tab >>Machine learning for improved density functional theory thermodynamics
2025 (English)In: Scientific Reports, E-ISSN 2045-2322, Vol. 15, no 1, article id 17212Article in journal (Refereed) Published
Abstract [en]

The predictive accuracy of density functional theory (DFT) for alloy formation enthalpies is often limited by intrinsic energy resolution errors, particularly in ternary phase stability calculations. In this work, we present a machine learning (ML) approach to systematically correct these errors, improving the reliability of first-principles predictions. A neural network model has been trained to predict the discrepancy between DFT-calculated and experimentally measured enthalpies for binary and ternary alloys and compounds. The model utilizes a structured feature set comprising elemental concentrations, atomic numbers, and interaction terms to capture key chemical and structural effects. By applying supervised learning and rigorous data curation we ensure a robust and physically meaningful correction. The model is implemented as a multi-layer perceptron (MLP) regressor with three hidden layers, optimized through leave-one-out cross-validation (LOOCV) and k-fold cross-validation to prevent overfitting. We illustrate the effectiveness of this method by applying it to the Al-Ni-Pd and Al-Ni-Ti systems, which are of interest for high-temperature applications in aerospace and protective coatings.

Place, publisher, year, edition, pages
Springer Nature, 2025
National Category
Bioinformatics (Computational Biology)
Identifiers
urn:nbn:se:uu:diva-557750 (URN)10.1038/s41598-025-02088-7 (DOI)001489973400020 ()40382420 (PubMedID)2-s2.0-105005454754 (Scopus ID)
Funder
Swedish Research Council, 1389.20.140Knut and Alice Wallenberg FoundationEU, European Research Council, 2022-06725Swedish Research Council
Available from: 2025-06-02 Created: 2025-06-02 Last updated: 2025-06-02Bibliographically approved
Miranda, I. P., Pankratova, M., Weissenhofer, M., Klautau, A. B., Thonig, D., Pereiro, M., . . . Bergman, A. (2025). Spin-lattice couplings in 3d ferromagnets: Analysis from first principles. Physical Review Materials, 9(2), Article ID 024409.
Open this publication in new window or tab >>Spin-lattice couplings in 3d ferromagnets: Analysis from first principles
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2025 (English)In: Physical Review Materials, E-ISSN 2475-9953, Vol. 9, no 2, article id 024409Article in journal (Refereed) Published
Abstract [en]

Magnetoelasticity plays a crucial role in numerous magnetic phenomena, including magnetocalorics, magnon excitation via acoustic waves, and ultrafast demagnetization, or the Einstein-de Haas effect. Despite a long-standing discussion on anisotropy-mediated magnetoelastic interactions of relativistic origin, the exchangemediated magnetoelastic parameters within an atomistic framework have only recently begun to be investigated. As a result, many of their behaviors and values for real materials remain poorly understood. Therefore, by using a proposed simple modification of the embedded cluster approach that reduces the computational complexity, we critically analyze the properties of exchange-mediated spin-lattice coupling parameters for elemental 3d ferromagnets (bcc Fe, fcc Ni, and fcc Co), comparing methods used for their extraction and relating their realistic values to symmetry considerations and orbitally decomposed contributions. Additionally, we investigate the effects of noncollinearity (spin temperature) and applied pressure on these parameters. For Fe, we find that singlesite rotations, associated with spin temperatures around 100 K, induce significant modifications, particularly in Dzyaloshinskii-Moriya-type couplings; in contrast, such interactions in Co and Ni remain almost configuration independent. Moreover, we demonstrate a notable change in the exchange-mediated magnetoelastic constants for Fe under isotropic contraction. Finally, the conversion between atomistic, quantum-mechanically derived parameters and the phenomenological magnetoelastic theory is discussed, which can be a useful tool towards larger and more realistic dynamics simulations involving coupled subsystems.

Place, publisher, year, edition, pages
American Physical Society, 2025
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-557199 (URN)10.1103/PhysRevMaterials.9.024409 (DOI)001432743000004 ()
Funder
Knut and Alice Wallenberg Foundation, 2018.0060Knut and Alice Wallenberg Foundation, 2021.0246Knut and Alice Wallenberg Foundation, 2022.0108eSSENCE - An eScience CollaborationCarl Tryggers foundation Swedish Energy AgencyEU, European Research Council, 854843-FASTCORRStandUpOlle Engkvists stiftelseSwedish Research Council, 2016-05980Swedish Research Council, 2019-05304Swedish Research Council, 2019-03666Swedish Research Council, 2023-04239Swedish Research Council, 2024-04986Swedish Research Council, 2022-06725
Available from: 2025-05-27 Created: 2025-05-27 Last updated: 2025-05-27Bibliographically approved
Rybakov, F. N., Eriksson, O. & Kiselev, N. S. (2025). Topological invariants of vortices, merons, skyrmions, and their combinations in continuous and discrete systems. Physical Review B, 111(13), Article ID 134417.
Open this publication in new window or tab >>Topological invariants of vortices, merons, skyrmions, and their combinations in continuous and discrete systems
2025 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 111, no 13, article id 134417Article in journal (Refereed) Published
Abstract [en]

Magnetic vortices and skyrmions are typically characterized by distinct topological invariants. This paper presents a unified approach for the topological classification of these textures, encompassing isolated objects and configurations where skyrmions and vortices coexist. Using homotopy group analysis, we derive topological invariants that form the free Abelian group, Z x Z. We provide an explicit method for calculating the corresponding integer indices in continuous and discrete systems. This unified classification framework extends beyond magnetism and is applicable to physical systems in general.

Place, publisher, year, edition, pages
American Physical Society, 2025
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-555797 (URN)10.1103/PhysRevB.111.134417 (DOI)001467608200001 ()2-s2.0-105002685345 (Scopus ID)
Funder
Swedish Research CouncilStandUpEU, European Research Council, 854843Knut and Alice Wallenberg FoundationKnut and Alice Wallenberg Foundation, KAW 2022.0108Knut and Alice Wallenberg Foundation, KAW 2022.0252EU, Horizon 2020, 856538
Available from: 2025-05-13 Created: 2025-05-13 Last updated: 2025-05-13Bibliographically approved
Gupta, D., Pankratova, M., Riepp, M., Pereiro, M., Sanyal, B., Ershadrad, S., . . . Boeglin, C. (2025). Tuning ultrafast demagnetization with ultrashort spin polarized currents in multi-sublattice ferrimagnets. Nature Communications, 16(1), Article ID 3097.
Open this publication in new window or tab >>Tuning ultrafast demagnetization with ultrashort spin polarized currents in multi-sublattice ferrimagnets
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2025 (English)In: Nature Communications, E-ISSN 2041-1723, Vol. 16, no 1, article id 3097Article in journal (Refereed) Published
Abstract [en]

Femtosecond laser pulses can be used to induce ultrafast changes of the magnetization in magnetic materials. Several microscopic mechanisms have been proposed to explain these observations, including the transport of ultrashort spin-polarized hot-electrons (SPHE). However, currently such ultrafast spin currents are only poorly characterized due to the measurement requirements for element and time resolution. Here, using time- and element-resolved X-ray magnetic circular dichroism alongside atomistic spin-dynamics simulations, we study the ultrafast transfer of the angular momentum from spin-polarized currents. We show that using a Co/Pt multilayer as a polarizer in a spin-valve structure, the SPHE drives the demagnetization of the two sub-lattices of the Fe74Gd26 film. This behaviour can be explained with two physical mechanisms; spin transfer torque and thermal fluctuations induced by the SPHE. We provide a quantitative description of the heat transfer of the ultrashort SPHE pulse to the Fe74Gd26 films, as well as the effect of spin-polarization of the SPHE current density responsible for the observed magnetization dynamics. Our work finally characterizes the spin-polarization of the SPHEs revealing unexpected opposite spin polarization to the Co magnetization.

Place, publisher, year, edition, pages
Springer Nature, 2025
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-557026 (URN)10.1038/s41467-025-58411-3 (DOI)001456731600007 ()40164666 (PubMedID)2-s2.0-105001649899 (Scopus ID)
Funder
StandUpSwedish Research Council, 2018-05973EU, European Research CouncilKnut and Alice Wallenberg FoundationSwedish Research Council, 05K19WO61Olle Engkvists stiftelse
Available from: 2025-05-22 Created: 2025-05-22 Last updated: 2025-05-22Bibliographically approved
Hultman, L., Mazur, S., Ankarcrona, C., Palmqvist, A., Abrahamsson, M., Antti, M.-L., . . . Berggren, M. (2024). Advanced materials provide solutions towards a sustainable world [Letter to the editor]. Nature Materials, 23(2), 160-161
Open this publication in new window or tab >>Advanced materials provide solutions towards a sustainable world
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2024 (English)In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 23, no 2, p. 160-161Article in journal, Letter (Other academic) Published
Place, publisher, year, edition, pages
Springer Nature, 2024
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-527720 (URN)10.1038/s41563-023-01778-9 (DOI)001186346600016 ()38307974 (PubMedID)
Available from: 2024-05-07 Created: 2024-05-07 Last updated: 2025-02-07Bibliographically approved
Projects
Application of atomistic materials theory [2008-05585_VR]; Uppsala UniversityMagnetocaloric materials and refrigeration for efficient use of electric energy in refrigerators and air conditioning systems - Magnetocalorics [2009-03351_VR]; Uppsala UniversityAtomära Spinndynamiksimuleringar med Applikationer inom Informationsteknologi [2009-03047_VR]; Uppsala UniversityDynamics of correlated electron systems [2009-06545_VR]; Uppsala UniversityDynamics of correlated electron systems [2009-08242_VR]; Uppsala UniversityElectronic Structure Theory with Applications to Modern Materials [2011-03226_VR]; Uppsala UniversityTheory of Magnonics [2012-02459_VR]; Uppsala UniversityNya magnetiska material för tillämpningar inom magnetisk kylning och permanentmagnetism [2012-04706_VR]; Uppsala UniversityDynamics of Materials [2013-08316_VR]; Uppsala UniversityGransport [2017-06815_VR]; Uppsala UniversityAtt hitta nya permanentmagneter med teori [P45404-1_Energi]; Uppsala UniversityFirst-principles Study of Functional Materials for Energy Storage: Electrochemical Interfaces and Advanced Spectroscopy [2020-00126_VR]; Uppsala UniversityElement specific investigations of ultrafast magnetisation dynamics [2021-05395_VR]; Uppsala UniversityUltrafast Magnonics [2022-02881_VR]; Uppsala UniversityAluminium carbonitride-based nanolaminates - a route to new materials [2022-03120_VR]; Uppsala UniversityMultiscale magnetization dynamics; development and applications [2023-04899_VR]; Uppsala University; Publications
Liu, Y., Miranda, I. P., Johnson, L., Bergman, A., Delin, A., Thonig, D., . . . Sjöqvist, E. (2024). Quantum Analog of Landau-Lifshitz-Gilbert Dynamics. Physical Review Letters, 133(26), Article ID 266704.
From minerals to functional magnets [2024-00262_VR]; Uppsala University
Organisations
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ORCID iD: ORCID iD iconorcid.org/0000-0001-5111-1374

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