Electronic correlations arising from anti-Stoner spin excitations: An ab initio study of itinerant ferro- and antiferromagnets Sebastian Paischer, David Eilmsteiner, Mikhail I. Katsnelson, Arthur Ernst, Paweł A. Buczek Physical Review B, 2024 The anti-Stoner excitations are a spin flips in which an electron is effectively promoted from a minority to a majority spin state, i.e., complementary to Stoner excitations and spin waves. Since their spectral power is negligible in strong itinerant ferromagnets and they are entirely absent in the ferromagnetic Heisenberg model, their properties and role in correlating electrons have scarcely been investigated. However, they are present in weak ferromagnets, fcc Ni being a prominent example. Both types of spin flips (down-to-up and up-to-down) must be treated equally in systems with degenerate spin-up and spin-down bands, particularly in antiferromagnets, for which we choose CrSb as a model system. For these two materials, we evaluate the strength of the effective interaction between the quasiparticles and the gas of virtual spin-flip excitations. To this end, we compute the corresponding self-energy taking advantage of our efficient ab initio numerical scheme [Phys. Rev. B 107, 134410 (2023)]. In Ni, we find that the band-structure renormalization caused by the anti-Stoner processes is weaker than that caused by Stoner-type magnons in the majority spin channel, but the two become comparable for minority spin carriers. The effect can be traced back primarily to the spectral strength of the respective spin excitations and the densities of the final available quasiparticle states in the scattering process. In the antiferromagnet, the situation is more complex and we observe that the electron-magnon interaction is sensitive not only to these densities of states but also critically to the spatial shapes of the coupling magnonic modes.
Correlations, disorder, and multimagnon processes in terahertz spin dynamics of magnetic nanostructures: A first-principles investigation Sebastian Paischer, David Eilmsteiner, Igor Maznichenko, Nadine Buczek, Khalil Zakeri, Arthur Ernst, Paweł A. Buczek Physical Review B, 2024 Understanding the impact of electronic correlations and disorder is essential for an accurate description of solids. Here, we study the role of correlations, disorder, and multimagnon processes in THz spin dynamics. We reveal that a significant part of the electron self-energy, which goes beyond the adiabatic local spin density approximation, arises from the interaction between electrons and a virtual magnon gas. This interaction leads to a substantial modification of the exchange splitting and a renormalization of magnon energies, in agreement with the experimental data. Finally, we establish a quantitative hierarchy of magnon relaxation processes based on first principles.
Fragile altermagnetism and orbital disorder in Mott insulator LaTiO3 I. V. Maznichenko, A. Ernst, D. Maryenko, V. K. Dugaev, E. Ya. Sherman, P. Buczek, S. S. P. Parkin, S. Ostanin Physical Review Materials, 2024 Based on ab initio calculations, we demonstrate that a Mott insulator ${\mathrm{LaTiO}}_{3}$ (LTO), not inspected previously as an altermagnetic material, shows the characteristic features of altermagnets, i.e., (i) fully compensated antiferromagnetism and (ii) $k$-dependent spin-split electron bands in the absence of spin-orbit coupling. The altermagnetic ground state of LTO is protected by the crystal symmetry and specifically ordered $d$ orbitals of Ti ions with the orbital momentum $l=2.$ The altermagnetism occurs when sites of Ti pairs in the unit cell are occupied by single electrons with $m=\ensuremath{-}1,{s}_{z}=+1/2$ and $m=+1,{s}_{z}=\ensuremath{-}1/2$ per site, with $m$ and ${s}_{z}\ensuremath{-}$ being the $z\text{\ensuremath{-}}$component of the orbital momentum and spin, respectively. By further simulating orbital disorder within the Green's function method, we disclose its damaging character on the spin splitting and the resulting altermagnetism. When the single-electron spin-polarized state at each Ti site is contributed almost equally by two or three ${t}_{2g}$ orbitals, LTO becomes antiferromagnetic. The effect of the spin-orbit coupling, which can cause orbital disorder and suppress altermagnetism, is discussed.
Emerging Two-Dimensional Conductivity at the Interface between Mott and Band Insulators I. V. Maznichenko, S. Ostanin, D. Maryenko, V. K. Dugaev, E. Ya. Sherman, P. Buczek, I. Mertig, M. Kawasaki, A. Ernst Physical Review Letters, 2024 Intriguingly, conducting perovskite interfaces between ordinary band insulators are widely explored, whereas similar interfaces with Mott insulators are still not quite understood. Here, we address the (001), (110), and (111) interfaces between the LaTiO_{3} Mott, and large band gap KTaO_{3} insulators. Based on first-principles calculations, we reveal a mechanism of interfacial conductivity, which is distinct from a formerly studied one applicable to interfaces between polar wideband insulators. Here, the key factor causing conductivity is the matching of oxygen octahedra tilting in KTaO_{3} and LaTiO_{3} which, due to a small gap in the LaTiO_{3} results in its sensitivity to the crystal structure, yields metallization of its overlayer and following charge transfer from Ti to Ta. Our findings, also applicable to other Mott insulators interfaces, shed light on the emergence of conductivity observed in LaTiO_{3}/KTaO_{3} (110) where the "polar" arguments are not applicable and on the emergence of superconductivity in these structures.
Spin textures induced in n-doped solid electrolytes I V Maznichenko, P Buczek, I Mertig, S Ostanin Journal of Physics D Applied Physics, 2023 A strongly insulating solid-state electrolyte may become conducting upon n-doping. On the basis of ab initio calculations, we demonstrate how the charge-to-spin conversion takes place in Li-doped lithium tantalate. Due to an excess of electrons induced by each Li dopant, the low-conduction 5d band of the nearest Ta shifts down and crosses the Fermi level. The band structure of the doped material displays its spin polarization, whilst the relatively large spin–orbit coupling stimulates the spin textures. Additionally, we anticipate that spin-orbitronic effects may be generated by the charge current via n-doped solid-state electrolytes.
Controlled Electronic and Magnetic Landscape in Self-Assembled Complex Oxide Heterostructures Dae‐Sung Park, Aurora Diana Rata, Rasmus Tindal Dahm, Kanghyun Chu, Yulin Gan, Igor Maznichenko, Sergey Ostanin, Felix Trier, Hionsuck Baik, Woo Seok Choi, Chel‐Jong Choi, Young Heon Kim, Gregory Jon Rees, Hafliði Pétur Gíslason, Paweł Adam Buczek, Ingrid Mertig, Mihai Adrian Ionescu, Arthur Ernst, Kathrin Dörr, Paul Muralt, Nini Pryds Advanced Materials, 2023 Complex oxide heterointerfaces contain a rich playground of novel physical properties and functionalities, which give rise to emerging technologies. Among designing and controlling the functional properties of complex oxide film heterostructures, vertically aligned nanostructure (VAN) films using a self‐assembling bottom‐up deposition method presents great promise in terms of structural flexibility and property tunability. Here, the bottom‐up self‐assembly is extended to a new approach using a mixture containing a 2Dlayer‐by‐layer film growth, followed by a 3D VAN film growth. In this work, the two‐phase nanocomposite thin films are based on LaAlO3:LaBO3, grown on a lattice‐mismatched SrTiO3001 (001) single crystal. The 2D‐to‐3D transient structural assembly is primarily controlled by the composition ratio, leading to the coexistence of multiple interfacial properties, 2D electron gas, and magnetic anisotropy. This approach provides multidimensional film heterostructures which enrich the emergent phenomena for multifunctional applications.
Nonlocal correlation effects due to virtual spin-flip processes in itinerant electron ferromagnets Sebastian Paischer, Giovanni Vignale, Mikhail I. Katsnelson, Arthur Ernst, Paweł A. Buczek Physical Review B, 2023 We present an ab initio method for electronic structure calculations, which accounts for the interaction of electrons and magnons in ferromagnets. While it is based on a many-body perturbation theory we approximate numerically complex quantities with quantities from time-dependent density functional theory. This results in a simple and affordable algorithm which allows us to consider more complex materials than those usually studied in this context ($3d$ ferromagnets) while still being able to account for the nonlocality of the self-energy. Furthermore, our approach allows for a relatively simple way to incorporate self-consistency. Our results are in a good agreement with experimental and theoretical findings for iron and nickel. Especially the experimental exchange splitting of nickel is predicted accurately within our theory. Additionally, we study the half-metallic ferromagnet NiMnSb concerning its nonquasiparticle states appearing in the band gap due to spin-flip excitations.
Defect-induced magnetism in homoepitaxial SrTiO3 A. D. Rata, J. Herrero-Martin, I. V. Maznichenko, F. M. Chiabrera, R. T. Dahm, S. Ostanin, D. Lee, B. Jalan, P. Buczek, I. Mertig, A. Ernst, A. M. Ionescu, K. Dörr, N. Pryds, D.-S. Park APL Materials, 2022 Along with recent advancements in thin-film technologies, the engineering of complex transition metal oxide heterostructures offers the possibility of creating novel and tunable multifunctionalities. A representative complex oxide is the perovskite strontium titanate (STO), whose bulk form is nominally a centrosymmetric paraelectric band insulator. By tuning the electron doping, chemical stoichiometry, strain, and charge defects of STO, it is possible to control the electrical, magnetic, and thermal properties of such structures. Here, we demonstrate tunable magnetism in atomically engineered STO thin films grown on STO (001) substrates by controlling the atomic charge defects of titanium (VTi) and oxygen (VO) vacancies. Our results show that the magnetism can be tuned by altering the growth conditions. We provide deep insights into its association to the following defect types: (i) VTi, resulting in a charge rearrangement and local spin polarization, (ii) VO, leading to weak magnetization, and (iii) VTi–VO pairs, which lead to the appearance of a sizable magnetic signal. Our results suggest that controlling charged defects is critical for inducing a net magnetization in STO films. This work provides a crucial step for designing magnetic STO films via defect engineering for magnetic and spin-based electronic applications.
Charge-to-spin conversion in the quasi-two-dimensional electron gas emerging at the hydrogen-doped interface between LiNbO3 and LaAlO3 I. V. Maznichenko, P. Buczek, I. Mertig, S. Ostanin Physical Review Materials, 2022 An oxide interface may become conducting when one oxide is polar, such as ${\mathrm{LaAlO}}_{3}$ (LAO) grown on ${\mathrm{SrTiO}}_{3}$ (001). We anticipate that the functional use of a solid electrolyte ${\mathrm{LiNbO}}_{3}$ (LiNO) in LAO/LiNO allows one to tune the quasi-two-dimensional electron gas (q2DEG) which emerges there. This phenomenon can be achieved by charging and discharging lithium niobate. In this paper, on the basis of ab initio calculations of the hydrogen-doped LAO/LiNO interface, we demonstrate how the q2DEG and its spin polarization appear. The out-of-plane electric polarization of LAO/LiNO forces the H dopants to accommodate at the Al-terminated interface. This results in the formation of the q2DEG, whose spatial extent is about 1.5 nm along the stacking direction. Since the spin-orbit coupling stimulates the spin textures in q2DEG, we believe that the charge current via the q2DEG may generate a variety of spin-orbitronic effects.
Elastic behavior of metal-assisted etched Si/SiGe superlattice nanowires containing dislocations Nadine Buczek (née Geyer), Michael Hanke, Pawel Buczek, Martin Dubslaff, Alexander A. Tonkikh, Bodo Fuhrmann, Hartmut S. Leipner Aip Advances, 2022 We systematically investigate structural parameters, such as shape, size, elastic strain, and relaxations, of metal-assisted etched vertically modulated Si/SiGe superlattice nanowires by using electron microscopy, synchrotron-based x-ray diffraction, and numerical linear elasticity theory. A vertical Si/Ge superlattice with atomically flat interfaces is grown by using molecular beam epitaxy on Si-buffered Si(001) substrates. The lattice constants for Si and Ge are 5.43 and 5.66 Å, respectively, which indicate a lattice mismatch of 4.2%. This results in a strained layer in the boundary between Si and Ge leading to dislocations. These substrates serve as the starting material for nanostructuring the surface by using metal-assisted etching. It is shown that the high quality crystalline structure is preserved in the fabrication process, while the lattice mismatch is partially relieved by dislocation formation. Despite this highly effective relaxation path, dislocations present in the parent superlattice do not vanish upon nanostructuring for wires with diameters of down to at least 80 nm. We relate these observations to the applicability of silicon-based nanowires for high-performance thermoelectric generators.
Structure and Magnetism of EuS on Bi2Se3(0001) Holger L. Meyerheim, Arthur Ernst, Katayoon Mohseni, Andrey Polyakov, Igor V. Maznichenko, Pawel A. Buczek, Alessandro Coati, Stuart S. P. Parkin Physica Status Solidi B Basic Research, 2021
Spin waves in disordered materials Paweł Buczek, Stefan Thomas, Alberto Marmodoro, Nadine Buczek, Xabier Zubizarreta, Martin Hoffmann, Timofey Balashov, Wulf Wulfhekel, Khalil Zakeri, Arthur Ernst Journal of Physics Condensed Matter, 2018
Quasi-Particles and Collective Excitations Evgueni V. Chulkov, Irina Sklyadneva, Mackillo Kira, Stephan W. Koch, Jose M. Pitarke, Leonid M. Sandratskii, Paweł Buczek, Kunie Ishioka, Jörg Schäfer, Martin Weinelt Dynamics at Solid State Surfaces and Interfaces, 2012
Ab initio study of the magnetic ordering in Si/Mn digital alloys M. M. Otrokov, A. Ernst, V. V. Tugushev, S. Ostanin, P. Buczek, L. M. Sandratskii, G. Fischer, W. Hergert, I. Mertig, V. M. Kuznetsov, E. V. Chulkov Physical Review B Condensed Matter and Materials Physics, 2011
Intralayer magnetic ordering in Ge/Mn digital alloys M. M. Otrokov, A. Ernst, S. Ostanin, G. Fischer, P. Buczek, L. M. Sandratskii, W. Hergert, I. Mertig, V. M. Kuznetsov, E. V. Chulkov Physical Review B Condensed Matter and Materials Physics, 2011
Ultrafast magnon generation in an Fe film on Cu(100) A. B. Schmidt, M. Pickel, M. Donath, P. Buczek, A. Ernst, V. P. Zhukov, P. M. Echenique, L. M. Sandratskii, E. V. Chulkov, M. Weinelt Physical Review Letters, 2010
Noncollinear spin structure in Dy-doped classical ferrimagnet AK Singh, K Mohseni, V Ney, A Ney, Y Guan, I Kostanovski, M Tangi, ... arXiv preprint arXiv:2601.05762 , 2026 2026
Ab initio modeling of resonant inelastic x-ray scattering from Ca2RuO4 DA Kukusta, LV Bekenov, PF Perndorfer, DV Vyalikh, PA Buczek, A Ernst, ... arXiv preprint arXiv:2511.18526 , 2025 2025
Magnon-electron scattering and non-Landau magnon decay, ab initio theories PA Buczek Johannes Kepler Universität Linz , 2025 2025
Unveiling Electron‐Phonon and Electron‐Magnon Interactions in the Weak Itinerant Ferromagnet LaCo 2 P 2 DY Usachov, K Ali, G Poelchen, M Mende, S Schulz, M Peters, K Bokai, ... Advanced Physics Research 4 (4), 2400137 , 2025 2025 Citations: 3
Electronic correlations arising from anti-Stoner spin excitations: An ab initio study of itinerant ferro- and antiferromagnets S Paischer, D Eilmsteiner, MI Katsnelson, A Ernst, PA Buczek Physical Review B 110 (16), 165121 , 2024 2024 Citations: 5
Fragile altermagnetism and orbital disorder in Mott insulator IV Maznichenko, A Ernst, D Maryenko, VK Dugaev, EY Sherman, ... Physical Review Materials 8 (6), 064403 , 2024 2024 Citations: 20
Correlations, disorder, and multimagnon processes in terahertz spin dynamics of magnetic nanostructures: A first-principles investigation S Paischer, D Eilmsteiner, I Maznichenko, N Buczek, K Zakeri, A Ernst, ... Physical Review B 109 (22), L220405 , 2024 2024 Citations: 14
Emerging two-dimensional conductivity at the interface between mott and band insulators IV Maznichenko, S Ostanin, D Maryenko, VK Dugaev, EY Sherman, ... Physical Review Letters 132 (21), 216201 , 2024 2024 Citations: 8
Emerging two-dimensional conductivity at Mott-band insulator interface IV Maznichenko, S Ostanin, D Maryenko, VK Dugaev, EY Sherman, ... arXiv preprint arXiv:2401.16813 , 2024 2024
Spin textures induced in n -doped solid electrolytes IV Maznichenko, P Buczek, I Mertig, S Ostanin Journal of Physics D: Applied Physics 56 (40), 405305 , 2023 2023 Citations: 2
Controlled electronic and magnetic landscape in self‐assembled complex oxide heterostructures DS Park, AD Rata, RT Dahm, K Chu, Y Gan, I Maznichenko, S Ostanin, ... Advanced Materials 35 (32), 2300200 , 2023 2023 Citations: 4
Nonlocal correlation effects due to virtual spin-flip processes in itinerant electron ferromagnets S Paischer, G Vignale, MI Katsnelson, A Ernst, PA Buczek Physical Review B 107 (13), 134410 , 2023 2023 Citations: 13
Correlated Electrons, Phase Transitions and Frustrated Magnetism in TiF 3 G Fernando, I Maznichenko, A Ernst, P Buczek, M Geilhufe APS March Meeting Abstracts 2023, W55. 012 , 2023 2023
Defect-induced magnetism in homoepitaxial SrTiO3 AD Rata, J Herrero-Martin, IV Maznichenko, FM Chiabrera, RT Dahm, ... APL materials 10 (9) , 2022 2022 Citations: 19
Charge-to-spin conversion in the quasi-two-dimensional electron gas emerging at the hydrogen-doped interface between and IV Maznichenko, P Buczek, I Mertig, S Ostanin Physical Review Materials 6 (6), 064001 , 2022 2022 Citations: 5
Elastic behavior of metal-assisted etched Si/SiGe superlattice nanowires containing dislocations M Hanke, P Buczek, M Dubslaff, AA Tonkikh, B Fuhrmann, HS Leipner AIP Advances 12 (4) , 2022 2022 Citations: 1
Open communication interfaces for Automatic Train Control systems: a vision or reality? L Schnieder, P Buczek Signal+ Draht 114 (3), 29-36 , 2022 2022
CBTC für Stadtbahnanwendungen L Schnieder, P von der Heide, P Buczek Der Nahverkehr, 34-37 , 2022 2022
Emergent quasi-two-dimensional electron gas between and and its prospectively switchable magnetism IV Maznichenko, S Ostanin, I Mertig, P Buczek Physical Review Materials 5 (11), 114001 , 2021 2021 Citations: 4
Eigenmodes of a disordered FeCo magnonic crystal at finite temperatures S Paischer, PA Buczek, N Buczek, D Eilmsteiner, A Ernst Journal of Physics: Condensed Matter 33 (33), 335804 , 2021 2021 Citations: 4
MOST CITED SCHOLAR PUBLICATIONS
Ultrafast magnon generation in an Fe film on Cu (100) AB Schmidt, M Pickel, M Donath, P Buczek, A Ernst, VP Zhukov, ... Physical review letters 105 (19), 197401 , 2010 2010 Citations: 179
Different dimensionality trends in the Landau damping of magnons in iron, cobalt, and nickel: Time-dependent density functional study P Buczek, A Ernst, LM Sandratskii Physical Review B—Condensed Matter and Materials Physics 84 (17), 174418 , 2011 2011 Citations: 127
Energies and Lifetimes of Magnons in Complex Ferromagnets:<? format?> A First-Principle Study of Heusler Alloys P Buczek, A Ernst, P Bruno, LM Sandratskii Physical review letters 102 (24), 247206 , 2009 2009 Citations: 113
Long-living terahertz magnons in ultrathin metallic ferromagnets HJ Qin, K Zakeri, A Ernst, LM Sandratskii, P Buczek, A Marmodoro, ... Nature communications 6 (1), 6126 , 2015 2015 Citations: 66
Ab initio theory of iron-based superconductors F Essenberger, A Sanna, P Buczek, A Ernst, L Sandratskii, EKU Gross Physical Review B 94 (1), 014503 , 2016 2016 Citations: 57
Interface electronic complexes and Landau damping of magnons in ultrathin magnets P Buczek, A Ernst, LM Sandratskii Physical Review Letters 106 (15), 157204 , 2011 2011 Citations: 52
Direct probing of the exchange interaction at buried interfaces K Zakeri, TH Chuang, A Ernst, LM Sandratskii, P Buczek, HJ Qin, Y Zhang, ... Nature Nanotechnology 8 (11), 853-858 , 2013 2013 Citations: 51
Magnon dispersion in thin magnetic films T Balashov, P Buczek, L Sandratskii, A Ernst, W Wulfhekel Journal of Physics: Condensed Matter 26 (39), 394007 , 2014 2014 Citations: 46
Paramagnons in FeSe close to a magnetic quantum phase transition: Ab initio study F Essenberger, P Buczek, A Ernst, L Sandratskii, EKU Gross Physical Review B—Condensed Matter and Materials Physics 86 (6), 060412 , 2012 2012 Citations: 42
Standing Spin Waves as a Basis for the Control of Terahertz Spin Dynamics:<? format?> Time Dependent Density Functional Theory Study P Buczek, A Ernst, LM Sandratskii Physical review letters 105 (9), 097205 , 2010 2010 Citations: 39
Nonmonotonic thickness dependence of spin wave energy in ultrathin Fe films: experiment and theory Y Zhang, P Buczek, L Sandratskii, WX Tang, J Prokop, I Tudosa, ... Physical Review B—Condensed Matter and Materials Physics 81 (9), 094438 , 2010 2010 Citations: 36
Plasmonic skyrmion lattice based on the magnetoelectric effect XG Wang, L Chotorlishvili, N Arnold, VK Dugaev, I Maznichenko, J Barnaś, ... Physical Review Letters 125 (22), 227201 , 2020 2020 Citations: 29
Periodic diffraction patterns for 1D quasicrystals P Buczek, L Sadun, J Wolny arXiv preprint cond-mat/0309008 , 2003 2003 Citations: 29
Lifetimes and chirality of spin waves in antiferromagnetic and ferromagnetic FeRh from the perspective of time-dependent density functional theory LM Sandratskii, P Buczek Physical Review B—Condensed Matter and Materials Physics 85 (2), 020406 , 2012 2012 Citations: 27
Impact of Atomic Structure on the Magnon Dispersion Relation: A Comparison Between and TH Chuang, K Zakeri, A Ernst, LM Sandratskii, P Buczek, Y Zhang, HJ Qin, ... Physical review letters 109 (20), 207201 , 2012 2012 Citations: 24
Magnons in disordered nonstoichiometric low-dimensional magnets P Buczek, LM Sandratskii, N Buczek, S Thomas, G Vignale, A Ernst Physical Review B 94 (5), 054407 , 2016 2016 Citations: 23
Spin dynamics of complex itinerant magnets PA Buczek Martin-Luther-Universität Halle-Wittenberg , 2009 2009 Citations: 21
Fragile altermagnetism and orbital disorder in Mott insulator IV Maznichenko, A Ernst, D Maryenko, VK Dugaev, EY Sherman, ... Physical Review Materials 8 (6), 064403 , 2024 2024 Citations: 20
Defect-induced magnetism in homoepitaxial SrTiO3 AD Rata, J Herrero-Martin, IV Maznichenko, FM Chiabrera, RT Dahm, ... APL materials 10 (9) , 2022 2022 Citations: 19
Spin waves in disordered materials P Buczek, S Thomas, A Marmodoro, N Buczek, X Zubizarreta, ... Journal of Physics: Condensed Matter 30 (42), 423001 , 2018 2018 Citations: 19