Article
Multidisciplinary Sciences
K. Komedera, J. Gatlik, A. Blachowski, J. Zukrowski, D. Rybicki, A. Delekta, M. Babij, Z. Bukowski
Summary: Investigation of EuFe2-xNixAs2 compounds with 3d and/or 4f magnetic order was done using Fe-57 and Eu-151 Mossbauer spectroscopy. The study found that Ni-substitution suppresses the spin-density wave order of Fe moments, while Eu localized moments still order with a spin reorientation as Ni concentration increases. The transition from antiferromagnetic to ferromagnetic 4f spins coincides with the disappearance of 3d spins order, showing strong coupling between Eu2+ ions and conduction electrons.
SCIENTIFIC REPORTS
(2021)
Article
Chemistry, Multidisciplinary
Alexander Herman, Stefan Kraus, Shigeru Tsukamoto, Lea Spieker, Vasile Caciuc, Tobias Lojewski, Damian Guenzing, Jan Dreiser, Bernard Delley, Katharina Ollefs, Thomas Michely, Nicolae Atodiresei, Heiko Wende
Summary: From macroscopic heavy-duty permanent magnets to nanodevices, precise control of magnetic properties in rare-earth metals is crucial for various daily life applications. In this study, a proof-of-concept approach using a dysprosium-iridium surface alloy and graphene adsorption is presented, enabling the tailored manipulation of magnetic properties. By selectively lifting magnetic 4f-metal atoms from the surface alloy through the adsorption of graphene, a giant magnetic anisotropy in dysprosium atoms is introduced. The successful introduction and demonstration of this concept provide a clear understanding of its underlying mechanism and pave the way for an alternative approach to modify the crystal field around 4f-atoms and their magnetic anisotropies.
Article
Materials Science, Multidisciplinary
Zhiyuan Zhao, Zhicheng Xie, Yiming Sun, Yumin Yang, Ying Cao, Lei Liu, Dong Pan, Na Lei, Zhongming Wei, Jianhua Zhao, Dahai Wei
Summary: Recently, magnetic multilayers composed of repetitive heavy metal/ferromagnetic bilayers have been extensively studied for their large Dyzaloshinskii-Moriya interaction (DMI) and perpendicular magnetic anisotropy. In this study, we report a bulklike enhancement of DMI strength through the number of stacking layers in [Co/Tb]N multilayers without introducing heavy metals. Our findings suggest the potential of rare-earth transition-metal based magnetic multilayers for skyrmion applications due to their tunable magnetic properties regarding magnetic chiral textures.
Article
Nanoscience & Nanotechnology
X. B. Liu, D. H. Ryan, Z. Altounian
Summary: The phase stability and magnetocrystalline anisotropy (MCA) of tetragonal Mn(Al1-xGax) with the L1(0)-type structure (P4/mmm) were investigated using first-principles density functional calculations. The results showed that replacing Al with Ga suppressed the formation of Mn-5(Al,Ga)(8) and improved the thermal stability of the L1(0) phase without significant changes in the total magnetic moment. The MCA was mainly contributed by Mn atoms and increased from 0.25 meV/f.u. (x = 0) to 0.34 meV/f.u. (x = 1). Doping with Ga enhanced the thermal stability of the L1(0) structure and increased the effective magnetic anisotropy field.
Article
Materials Science, Multidisciplinary
Ruiwen Xie, Hongbin Zhang
Summary: This study investigates the magnetization and electronic structure of the CeCo5 system using the DFT + DMFT approach, revealing a significant reduction in the magnetic moment of the Ce-4f shell and contrasting magnetic moment changes of Ce in different alloys.
Article
Materials Science, Multidisciplinary
Shuxing Li, Mahdi Amachraa, Chi Chen, Le Wang, Zhenbin Wang, Shyue Ping Ong, Rong-Jun Xie
Summary: In this study, the key descriptors of Eu(II)-host interactions were introduced to predict the 5d-to-4f energy gap in the crystal, and a high-throughput screening of 223 nitride materials led to the discovery and experimental validation of (Sr,Ba)(3)Li4Si2N6:Eu(II) with near-infrared emissions and high quantum efficiencies. This work provides a cost-efficient computational approach for discovering phosphors with desired emissions.
Article
Chemistry, Physical
Wen-Bin Wu, Julia Kasiuk, Janusz Przewoznik, Czeslaw Kapusta, Ivan Svito, Dang Thanh Tran, Hung Manh Do, Hung Manh Dinh, Johan Akerman, Thi Ngoc Anh Nguyen
Summary: We studied the magnetoresistance mechanisms in a Pt/[Co/Pt]x5 film consisting of a ferromagnetic [Co/Pt]x5 layer with strong perpendicular magnetic anisotropy and a nonmagnetic Pt layer with strong spin-orbit coupling. Two competing contributions, sin2 theta and cos4 theta, were revealed in the electrical resistance of the film at different angles and magnetic fields, corresponding to the out-of-plane rotation of the magnetization M(theta) perpendicularly to the electric current. The cos4 theta contribution is attributed to the anisotropic magnetoresistance of the ferromagnetic layer, while the sin2 theta contribution is mainly associated with the spin Hall magnetoresistance originating from the Pt layer. The strong influence of the electric current on the magnetization of the film is of high relevance for magnetic memory design technologies.
APPLIED SURFACE SCIENCE
(2024)
Article
Chemistry, Physical
Dmitry Yu. Usachov, Daria Glazkova, Artem V. Tarasov, Susanne Schulz, Georg Poelchen, Kirill A. Bokai, Oleg Yu. Vilkov, Pavel Dudin, Kurt Kummer, Kristin Kliemt, Cornelius Krellner, Denis V. Vyalikh
Summary: To efficiently utilize the magnetic functionalities in novel lanthanides-based materials, it is necessary to probe the atomic-layer resolved magnetic properties using complementary methods. This study demonstrates that 4f photoelectron spectroscopy is highly sensitive to the collective orientation of 4f magnetic moments and can be a powerful tool for characterizing related properties. The systematic study on a family of layered crystalline 4f-materials reveals that the 4f moments at the surfaces experience a strong reorientation due to changes in the crystal-electric field. Hence, this research is of great importance for efficient control of magnetic properties in layered 4f-systems.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Physical
P. Kral, J. Kastil, M. Klicpera, P. Dolezal, J. Prokleska, L. Havela, J. Prchal
Summary: Ce2Pd2In is a rare example of a Ce-based ferromagnet among a group of R2T2X intermetallics, with a stable 4f magnetism under pressure up to 3 GPa. The transition between ferromagnetic and antiferromagnetic phases in Ce2Pd2In occurs at an unusual temperature, and the magnetic properties are affected by hydrostatic pressure but not uniaxial pressure along the tetragonal c-axis.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Physical
Dakota M. Merriles, Kimberly H. Tomchak, Joshua C. Ewigleben, Michael D. Morse
Summary: The bond dissociation energies of EuO, TmO, and YbO were measured using resonant two-photon ionization spectra. The precision of the results was significantly improved compared to previous values. In addition, the ionization energy of TmO was measured, and the molecules were found to possess a high density of electronic states at the energy of the ground separated atom limit.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Yingzheng Gao, Sergio Vlaic, Tommaso Gorni, Luca de'Medici, Sylvain Clair, Dimitri Roditchev, Stephane Pons
Summary: By moving individual Fe-porphyrin-based molecules with a scanning tunneling microscope, we have successfully controlled their magnetic states in the vicinity of a herringbone-reconstructed Au(111) surface containing a Br atom. We obtained different magnetic regimes and explored their theoretical explanations, including the generation of charge fluctuations and mixed valency in the molecule-surface hybrids. This study demonstrates the potential of utilizing charge fluctuations to manipulate quantum magnetic states.
Article
Physics, Multidisciplinary
Yuanyuan Yang, Qisi Wang, Shaofeng Duan, Hongliang Wo, Chaozhi Huang, Shichong Wang, Lingxiao Gu, Dao Xiang, Dong Qian, Jun Zhao, Wentao Zhang
Summary: In this study, high-resolution time- and angle-resolved photoemission measurements were conducted on FeSe superconductors. Two critical excitation fluences corresponding to ultrafast electronic phase transitions were discovered. The importance of two equilibrium electronic phase transitions and the contribution of the structural transition in FeSe were determined.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Physical
J-P Lehtio, T. Hadamek, M. Kuzmin, P. Laukkanen, A. A. Demkov
Summary: By utilizing scanning tunneling spectroscopy (STS), it was found that the conduction band (CB) bottom at the surface of epitaxial Eu2O3 grown on GaN(0001)/ Si (111) substrates is solely formed by an unoccupied Eu 4f state, which is 0.8 eV above the Fermi level. This state does not overlap with unoccupied Eu 5d6s states, which are located more than 2 eV higher than the bottom of the 4f band.
Article
Chemistry, Physical
Luu Huu Nguyen, Pham Thanh Phong, Pham Hong Nam, Do Hung Manh, Nguyen Thi Kim Thanh, Le Duc Tung, Nguyen Xuan Phuc
Summary: This paper explores the characteristics of magnetic inductive heating power, presenting three distinct regions and analyzing the impact of anisotropy on nanoparticle properties. The potential to enhance heating power by increasing anisotropy is investigated and deduced. In high-viscosity media, magnetic nanoparticles in the N- and/or NB-regions are generally more suitable for application.
Article
Physics, Multidisciplinary
Stefano Trivini, Jon Ortuzar, Katerina Vaxevani, Jingchen Li, F. Sebastian Bergeret, Miguel A. Cazalilla, Jose Ignacio Pascual
Summary: We demonstrate that a single tunneling electron can induce pair breaking excitations in a proximitized gold film containing magnetic impurities. By combining scanning tunneling spectroscopy with theoretical modeling, we map the excitation spectrum of a Fe-porphyrin molecule on the Au/Vo100 thorn proximitized surface to a manifold of entangled Yu-Shiba-Rusinov and spin excitations. Pair excitations only emerge in the tunneling spectra as peaks outside the spectral gap in the strong coupling regime, where a bound quasiparticle in the ground state ensures the even fermion parity of the excitation. Our results unravel the quantum nature of magnetic impurities on superconductors and demonstrate that pair excitations unequivocally reveal the parity of the ground state.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Condensed Matter
Eleanor Lawrence Bright, Lei Xu, Lottie M. Harding, Ross Springell, Andrew C. Walters, Martin Sundermann, Mirian Garcia-Fernandez, Stefano Agrestini, Roberto Caciuffo, Gerrit van der Laan, Gerard H. Lander
Summary: Resonant inelastic x-ray scattering (RIXS) was used to study epitaxial films of alpha-U3O8 and UN, with an incident energy tuned to the uranium N-4,N-5 absorption edges. The multiplets associated with a 5f(1) configuration were observed for U3O8, but the predicted strong transition at a transfer energy of 1.67 eV was not observed. For the 5f-itinerant system UN, no sharp transitions were observed, indicating a predominantly 5f(3) configuration in this band-like semi-metallic system. These findings provide important information on these materials and the potential of RIXS at the uranium N edge for actinide research.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Nanoscience & Nanotechnology
Pedram Abbasi, Nozomi Shirato, Rishi E. Kumar, Isabel V. Albelo, Matthew R. Barone, Deniz N. Cakan, Ma. de la Paz Cruz-Jauregui, Sarah Wieghold, Darrell G. Schlom, Volker Rose, Tod A. Pascal, David P. Fenning
Summary: In this study, the role of polarization on the surface structure and chemistry of a model ferroelectric BaTiO3 thin film was investigated using synchrotron X-ray scanning tunneling microscopy (SX-STM) and computational absorption spectroscopy. The results showed that polarization switching increased the X-ray absorption intensity and modulated the surface structures. Theoretical calculations supported these findings and provided evidence for the effect of polarization switching on the binding strength with molecular O2. This study advances the understanding of the surface chemistry and electronic structure of ferroelectrics, which can inform the design of interfaces with tailored properties.
ACS APPLIED NANO MATERIALS
(2023)
Article
Physics, Applied
Prosper Ngabonziza, Jisung Park, Wilfried Sigle, Peter A. van Aken, Jochen Mannhart, Darrell G. Schlom
Summary: We have developed a synthetic route to achieve high electron mobility at room temperature in La:BaSnO3/SrZrO3 heterostructures grown on various oxide substrates. The room-temperature mobilities obtained were 157, 145, and 143 cm(2) V(-1) s(-1) for heterostructures grown on DyScO3 (110), MgO (001), and TbScO3 (110) crystalline substrates, respectively. This was achieved by growing a SrZrO3 buffer layer at high temperature using pulsed laser deposition to reduce dislocation density, followed by the epitaxial growth of a La:BaSnO3 active layer using molecular-beam epitaxy. The results provide a promising pathway for achieving high mobility in buffered La:BaSnO3 films on oxide substrates with lattice mismatches.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Physical
Stephanie D. Matson, Jiaxin Sun, Jason J. Huang, Don J. Werder, Darrell G. Schlom, Andrej Singer
Summary: Renewable energy sources such as solar and wind are necessary to combat global warming, but their intermittent generation requires large-scale grid energy storage, unlike coal-based power plants. Sodium-ion batteries show promise, but their structural rearrangements during intercalation make them less durable. In this study, we synthesized epitaxial NaxCoO2 films that allow electrochemical extraction of sodium ions, providing a foundation for future studies on interfaces and structural changes in sodium-ion batteries.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Materials Science, Coatings & Films
Tobias Schwaigert, Salva Salmani-Rezaie, Matthew R. Barone, Hanjong Paik, Ethan Ray, Michael D. Williams, David A. Muller, Darrell G. Schlom, Kaveh Ahadi
Summary: Strain-engineering is used to tune the instabilities of incipient ferroelectrics. High-quality KTaO3 thin films are grown by molecular-beam epitaxy. Excess potassium and a combination of ozone and oxygen are supplied with the TaO2 (or tantalum) molecular beams to grow the films with atomically abrupt interfaces. Atomic force microscopy reveals atomic steps at the film surface. Reciprocal space mapping demonstrates coherent strain to the substrates when the films are thin enough.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Materials Science, Coatings & Films
Thomas J. Smart, Felix V. E. Hensling, Dong Yeong Kim, Lena N. Majer, Y. Eren Suyolcu, Dominik Dereh, Darrell G. Schlom, Debdeep Jena, Jochen Mannhart, Wolfgang Braun
Summary: This work investigates the behavior of aluminum sources in oxide thermal laser epitaxy and identifies two distinct operating regimes. At high laser-beam fluences, the source emits reproducible fluxes independent of oxygen pressure. At lower beam fluences, the flux increases with increasing oxygen pressure due to suboxide formation. The study demonstrates reproducible rate control over a wide range and highlights the advantages of thermal laser epitaxy over oxide molecular-beam epitaxy in handling aluminum sources.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Chemistry, Multidisciplinary
Haonan Jin, Wancong Tan, Yizhou Liu, Kejing Ran, Raymond Fan, Yanyan Shangguan, Yao Guang, Gerrit van der Laan, Thorsten Hesjedal, Jinsheng Wen, Guoqiang Yu, Shilei Zhang
Summary: In this study, we introduce a novel mechanism for the controlled stabilization of emergent monopoles and demonstrate that magnetic skyrmion strings can be folded into monopoles. Conversely, monopoles can act as seeds out of which the entire string structure can unfold. Resonant elastic X-ray scattering is used to observe the reversible evolution from monopole to string, resulting in the emergence of a pure monopole lattice on the surface. This provides new insight into topological defects and establishes the emergent monopole lattice as a new 3D topological phase.
Article
Nanoscience & Nanotechnology
David M. Burn, Jheng-Cyuan Lin, Ryuji Fujita, Barat Achinuq, Joshua Bibby, Angadjit Singh, Andreas Frisk, Gerrit van der Laan, Thorsten Hesjedal
Summary: The TSSs in TIs provide exciting possibilities for dissipationless spin transport. However, using high-quality single-crystalline TI films limits the amount of spin current that can be pumped due to a single pair of spin-momentum locked channels. On the other hand, using nanocrystalline TI films can effectively increase the number of spin channels available for spin pumping. This study demonstrates spin pumping from a FM layer through a TI layer and into a FM spin sink using x-ray based ferromagnetic resonance technique.
Article
Chemistry, Physical
Amir A. Haghighirad, Matthew T. Klug, Liam Duffy, Junjie Liu, Arzhang Ardavan, Gerrit van der Laan, Thorsten Hesjedal, Henry J. Snaith
Summary: Substitution of Co2+ into methylammonium lead triiodide lattice imparts magnetic behavior while maintaining photovoltaic performance. Co2+ ions are used as probes to sense the local electronic environment of Pb, revealing their incorporation into the perovskite. This work provides a comprehensive understanding of transition metal incorporation, opening the gateway for developing novel perovskite materials and devices.
Article
Physics, Applied
Emily Amonette, Prabin Dulal, Dylan Sotir, Matthew Barone, Darrell Schlom, Nikolas J. Podraza
Summary: TbScO3 is a wide bandgap semiconductor used in charge trap memory devices and as an alternate gate dielectric. It has an orthorhombic crystal structure, leading to optical anisotropy. Generalized ellipsometric spectra were measured for different orientations of TbScO3 single crystals, revealing a direct bandgap at 6.50 eV and critical point transitions above the gap at 6.99, 7.14, 7.16, 7.21, and 7.42 eV.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Condensed Matter
R. Sant, A. De Vita, V Polewczyk, G. M. Pierantozzi, F. Mazzola, G. Vinai, G. van der Laan, G. Panaccione, N. B. Brookes
Summary: Polarization dependent x-ray absorption spectroscopy was used to study the magnetic ground state and orbital occupation in VI3 van der Waals crystals. The effects of symmetry reduction and hybridization between vanadium and ligand states were evaluated. The results suggest that the insulating ground state is stabilized by Mott correlation effects rather than a Jahn-Teller mechanism, and provide insights for studying the spectroscopic properties of other van der Waals halides.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Instruments & Instrumentation
Gerrit van der Laan, Thorsten Hesjedal
Summary: Element-specific spectroscopies using synchrotron-radiation provide unique insights into materials properties. X-ray detected ferromagnetic resonance (XFMR) allows studying the magnetization dynamics of magnetic spin structures. Recent developments in X-ray scattering techniques reveal the precessional magnetization dynamics of ordered spin structures, providing valuable information for the engineering of high-density and low-energy consumption data processing solutions.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
(2023)
Article
Materials Science, Multidisciplinary
C. Love, J. E. Beevers, B. Achinuq, R. Fan, T. Susaki, K. Matsuzaki, V. K. Lazarov, S. S. Dhesi, G. van der Laan, S. A. Cavill
Summary: The size of the orbital moment in bulklike epitaxial Fe3O4 films on yttria-stabilized zirconia (111) substrates has been determined using ferromagnetic resonance (FMR) spectroscopy and x-ray magnetic circular dichroism (XMCD). Annealing the films improves their stoichiometry and microstructure, allowing for the recovery of bulklike properties. Both FMR and XMCD techniques provide evidence for the presence of a finite orbital moment in Fe3O4, with a spectroscopic splitting factor g approximately 2.18.
Article
Materials Science, Multidisciplinary
Marisel Di Pietro Martinez, Alexis Wartelle, Carlos Herrero Martinez, Farid Fettar, Florent Blondelle, Jean-Francois Motte, Claire Donnelly, Luke Turnbull, Feodor Ogrin, Gerrit van der Laan, Horia Popescu, Nicolas Jaouen, Flora Yakhou-Harris, Guillaume Beutier
Summary: In recent years, there has been increased interest in expanding from 2D to 3D systems in the magnetism community. This has led to the need for new characterization techniques, including tomographic imaging, to explore new geometries and broaden knowledge on magnetic textures in thick samples. This study presents a new tomographic technique based on Fourier transform holography, which overcomes the phase problem inherent to reciprocal-space-based techniques and allows for investigation of thicker samples.
Article
Materials Science, Multidisciplinary
Xiaodong Xie, Kejing Ran, Yizhou Liu, Raymond Fan, Wancong Tan, Haonan Jin, Manuel Valvidares, Nicolas Jaouen, Haifeng Du, Gerrit van der Laan, Thorsten Hesjedal, Shilei Zhang
Summary: We have identified a three-dimensional skyrmion side-face state in chiral magnets, which is composed of a thin layer of modulated surface spirals and an array of phase-locked skyrmion screws. Using resonant elastic x-ray scattering, we observed a characteristic X-shaped magnetic diffraction pattern that resembles Photo 51 of the DNA double-helix diffraction. By measuring both thin plates and bulk Cu2OSeO3 crystals in the field-in-plane geometry, we were able to unambiguously identify the modulated skyrmion strings and retrieve their chirality and helix angle. The breaking of translational symmetry along the side faces suppresses the bulk-favored conical state and provides a previously overlooked stabilization mechanism for the skyrmion lattice phase.
