Article
Multidisciplinary Sciences
Jia-nan Liu, Xu Yang, Haopu Xue, Xue-song Gai, Rui Sun, Yang Li, Zi-Zhao Gong, Na Li, Zong-Kai Xie, Wei He, Xiang-Qun Zhang, Desheng Xue, Zhao-Hua Cheng
Summary: With decreasing thickness of topological insulator thin films, single-particle band theory is insufficient to explain their band structures. This study reconstructs the surface-state coupling in ultrathin films using screened Coulomb interaction and finds that the magnitude of the mass gap agrees well with experimental results.
NATURE COMMUNICATIONS
(2023)
Article
Nanoscience & Nanotechnology
Asish K. Kundu, Sukanta Barman, Krishnakumar S. R. Menon
Summary: Surface termination has a significant impact on the metal-insulator transition (MIT) of V2O3 films, showing that MIT can be partially or fully suppressed near the surface region depending on the terminations. The redistribution of spectral weight and its transfer from high-to-low-binding energy regimes suggest the importance of electron-electron interactions in the strongly correlation-driven MIT in this system.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Materials Science, Coatings & Films
Saadia Nasir, Walter J. Smith, Thomas E. Beechem, Stephanie Law
Summary: Bi2Se3 is a widely studied 3D topological insulator with potential applications in optics, electronics, and spintronics. When the thickness of the films decreases to less than approximately 6 nm, the top and bottom surface states couple, resulting in the opening of a small gap at the Dirac point. In the 2D limit, Bi2Se3 may exhibit quantum spin Hall states. However, growing coalesced ultrathin Bi2Se3 films with a controllable thickness and typical triangular domain morphology in the few nanometer range is challenging.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Materials Science, Multidisciplinary
Shigemi Terakawa, Shinichiro Hatta, Hiroshi Okuyama, Tetsuya Aruga
Summary: We report on the formation of triple-atomic-layer metal films on Si(111) by depositing Mg onto In double-layer films. The (In, Mg) triple-layer phase exhibits a unique electronic structure, characterized by a circular Fermi surface composed of two circles with different radii.
Article
Nanoscience & Nanotechnology
Yuri D. Glinka, Junzi Li, Tingchao He, Xiao Wei Sun
Summary: Using transient absorption spectroscopy, researchers demonstrate that ultrafast carrier dynamics in ultrathin Bi2Se3 films are driven by two-photon excitation and polar optical phonon cascade emission, with the relaxation dynamics being influenced by the Dirac surface states and the presence of Dirac cones with different energies. The results suggest that a specific Dirac surface state acts as a valve, affecting the relaxation of electrons, resulting in detectable free carrier absorption.
Article
Chemistry, Multidisciplinary
Lisa S. Walter, Amelie Axt, James W. Borchert, Theresa Kammerbauer, Felix Winterer, Jakob Lenz, Stefan A. L. Weber, R. Thomas Weitz
Summary: In organic electronics, grain boundaries have a critical impact on charge transport. However, they are often hidden within the film and difficult to observe. By studying a minimal model system of thin films, it is found that grain boundaries can be either energetic barriers or valleys, and their influence is particularly pronounced at low charge-carrier densities. Furthermore, processing conditions that can control the type and energetic height of grain boundaries are identified.
Article
Materials Science, Multidisciplinary
Sudhanshu Gautam, V Aggarwal, Bheem Singh, Rahul Kumar, J. S. Tawale, B. S. Yadav, R. Ganesan, V. N. Singh, S. P. Singh, M. Senthil Kumar, S. S. Kushvaha
Summary: Thin films of Bi2Se3 were deposited on various substrates using magnetron sputtering. The films were found to have good crystalline quality, pure rhombohedral phase, and truncated hexagonal morphology. The optical bandgap of the films was in the range of 1.40-1.48 eV, and they showed potential for the development of futuristic devices.
JOURNAL OF MATERIALS RESEARCH
(2023)
Article
Chemistry, Multidisciplinary
Jie Xu, Changle Mu, Mingshu Chen
Summary: The metal-oxide interface is crucial in catalysis and understanding the structure and effect on catalytic performance of Cu-SiOx interface is challenging. In this study, ultrathin SiOx films were prepared and characterized to find that they can grow nearly layer-by-layer on the Cu(111) surface.
Article
Chemistry, Multidisciplinary
Linyi Li, Yantao Yu, Peng Li, Jinxin Liu, Lihan Liang, Luyang Wang, Yu Ding, Xiaocang Han, Jiamin Ji, Shengli Chen, Dehui Li, Pan Liu, Shunping Zhang, Mengqi Zeng, Lei Fu
Summary: Perovskite materials have attracted significant attention due to their diverse species and remarkable physical properties. Ultrathin perovskites, compared to bulk crystals, offer more composition options. By constructing an oriented solvent microenvironment, ultrathin perovskites with alterable composition and structure can be synthesized.
ADVANCED MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
Hanbum Park, Kwangsik Jeong, InHee Maeng, Kyung Ik Sim, Sachin Pathak, Jonghoon Kim, Seok-Bo Hong, Taek Sun Jung, Chul Kang, Jae Hoon Kim, Jongill Hong, Mann-Ho Cho
Summary: Researchers induced dehybridization of ultrathin topological insulator films by breaking inversion symmetry between surfaces, leading to enhanced spin-charge conversion efficiency. By growing the film on an oxygen-deficient transition-metal oxide, they observed up to a 2.4 times increase in SCC efficiency through this method.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Physics, Multidisciplinary
C. Clavaud, M. Maza-Cuello, C. Fretigny, L. Talini, T. Bickel
Summary: This study reports on the impact of intermolecular forces on the fluctuations of supported liquid films, demonstrating that these forces have a strong influence on the dynamics of the film interface at lower frequencies. Experimental data spanning three frequency decades align well with theoretical predictions considering van der Waals forces, highlighting the significance of intermolecular forces on thermal fluctuations in nanoscale confined fluids.
PHYSICAL REVIEW LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Seungbae Oh, Sudong Chae, Minho Kwon, Jungyoon Ahn, Chaeheon Woo, Kyung Hwan Choi, Jiho Jeon, Xue Dong, Tae Yeong Kim, Ghulam Asghar, Hanyoung Kim, Hyun-jong Paik, Hak Ki Yu, Jae-Young Choi
Summary: This study discovered a single-chain atomic crystal Mo3Se3-, which could be uniformly dispersed in an organic solvent and showed enhanced stability and mechanical properties through surface modification, indicating its potential applications.
Article
Engineering, Electrical & Electronic
Weibing Yang, Ke Chen, Leila Kasaei, Leonard C. Feldman, Daniel Cunnane, Boris S. Karasik, Xiaoxing Xi
Summary: Ultrathin superconducting MgB2 films were successfully grown on carbon-terminated SiC substrates using Hybrid Physical-Chemical Vapor Deposition (HPCVD). The thinnest superconducting films were studied in terms of their thickness dependence. The 2 nm thick MgB2 film exhibited a superconducting transition temperature Tc = 27.2 K, a self-field critical current density Jc(3K, 0T) = 2 x 10(7) A/cm(2), and a normal-state sheet resistance R-s = 44.5 omega/sq near the transition, with a root-mean-square roughness of 0.62 nm. These characteristics make the HPCVD-grown ultrathin MgB2 films highly attractive for superconducting electronic applications.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Multidisciplinary Sciences
Eva Arianna Aurelia Pogna, Leonardo Viti, Antonio Politano, Massimo Brambilla, Gaetano Scamarcio, Miriam Serena Vitiello
Summary: Through near-field microscopy, researchers have explored the rich physics of layered topological insulators Bi2Se3 and Bi2Te2.2Se0.8, revealing the collective modes dominating the optical response in thin flakes, as well as the propagation of phonon-polariton modes influenced by the topological surface states.
NATURE COMMUNICATIONS
(2021)
Article
Physics, Condensed Matter
Holger L. Meyerheim, Arthur Ernst, Katayoon Mohseni, Andrey Polyakov, Igor Maznichenko, Pawel A. Buczek, Alessandro Coati, Stuart S. P. Parkin
Summary: The study investigates the rocksalt-type ferromagnetic insulator EuS grown on Bi(2)Se(3) and reveals its structural and magnetic properties through experimental and computational methods, resolving previous conflicting conclusions. It found a magnetic proximity effect and complex magnetic ordering between EuS and Bi2Se3.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Hyeon Han, Hua Zhou, Charles Guillemard, Manuel Valvidares, Arpit Sharma, Yan Li, Ankit K. Sharma, Ilya Kostanovskiy, Arthur Ernst, Stuart S. P. Parkin
Summary: This study uses the hydrogen spillover method to tailor the properties of SrRuO3 thin films by incorporating hydrogen. It is found that the magnetization and Curie temperature of the films are significantly reduced, and the structure evolves from an orthorhombic to a tetragonal phase with increasing hydrogen content. In situ crystal truncation rod measurements show that the structural phase transition is related to tilting of the RuO6 octahedral units. Density functional theory analysis demonstrates that the significant changes in magnetization result from shifts in the Fermi level. These findings provide new insights into the physical properties of SrRuO3 through the modulation of its lattice symmetry and emergent physical phenomena using the hydrogen spillover technique.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Alexandra Yu. Vyazovskaya, Evgeniy K. K. Petrov, Yury M. M. Koroteev, Mihovil Bosnar, Igor V. V. Silkin, Evgueni V. V. Chulkov, Mikhail M. M. Otrokov
Summary: Using relativistic spin-polarized density functional theory calculations, the magnetism, electronic structure, and topology of thallium gadolinium dichalcogenides (TlGdZ2) and their superlattices are investigated. The results show that TlGdZ2 exhibits antiferromagnetic exchange coupling both within and between the Gd layers, leading to a complex magnetic structure. It is also found that constructing superlattices with TlGdZ2 and non-magnetic 3D topological insulators can potentially achieve a 3D magnetic topological insulator state.
Article
Physics, Applied
Nerea Ontoso, C. K. Safeer, Franz Herling, Josep Ingla-Aynes, Haozhe Yang, Zhendong Chi, Beatriz Martin-Garcia, Inigo Robredo, Maia G. Vergniory, Fernando de Juan, M. Reyes Calvo, Luis E. Hueso, Felix Casanova
Summary: This study investigates spin-charge interconversion (SCI) in a graphene-based lateral spin valve combined with low-symmetry MoTe2. The researchers observe three different SCI components, one orthogonal and two nonorthogonal, providing valuable insights into SCI processes in low-symmetry materials. The large SCI signals obtained at room temperature, along with the versatility of the 3D-current configuration, offer feasibility and flexibility for designing the next generation of spin-based devices.
PHYSICAL REVIEW APPLIED
(2023)
Article
Physics, Condensed Matter
Rimpy Saini, Devisharan Gautam, Sumalay Roy
Summary: Investigations of single and bilayers of bismuth are important in the field of condensed matter physics and material sciences due to its exotic electronic properties. In this study, a new organic method using the Langmuir-Blodgett technique was introduced to synthesize bismuth multi-bilayers. The analysis of the thin films showed the highly periodic stacking of bismuth bilayers with well-separated electronic states. The large separations between bilayers and between the substrate and bilayers minimized the electronic interactions.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Chemistry, Multidisciplinary
Nitish Mathur, Fang Yuan, Guangming Cheng, Sahal Kaushik, Inigo Robredo, Maia G. Vergniory, Jennifer Cano, Nan Yao, Song Jin, Leslie M. Schoop
Summary: In this study, a unique internal interface known as a merohedral twin boundary was discovered in chemically synthesized single-crystal nanowires of CoSi. Scanning transmission electron microscopy revealed that this internal interface is a (001) twin plane connecting two enantiomeric counterparts. Ab initio calculations showed the presence of localized internal Fermi arcs at the (001) twin plane, distinct from external Fermi arcs and bulk states. These merohedrally twinned CoSi nanowires provide an ideal platform for exploring topological properties associated with internal interfaces in Weyl semimetals.
Article
Nanoscience & Nanotechnology
Kun-Rok Jeon, Binoy Krishna Hazra, Jae-Keun Kim, Jae-Chun Jeon, Hyeon Han, Holger L. Meyerheim, Takis Kontos, Audrey Cottet, Stuart S. P. Parkin
Summary: This study reports the spin-triplet supercurrent spin valves in chiral antiferromagnetic Josephson junctions and a direct-current superconducting quantum interference device. By utilizing the Berry curvature-induced fictitious magnetic fields and the non-collinear atomic-scale spin arrangement, long-range triplet Cooper pairing is achieved in the chiral antiferromagnet Mn3Ge. The observed supercurrent spin-valve behaviors under a small magnetic field and the direct-current superconducting quantum interference device functionality are theoretically verified.
NATURE NANOTECHNOLOGY
(2023)
Article
Physics, Multidisciplinary
J. Sanchez-Barriga, O. J. Clark, M. G. Vergniory, M. Krivenkov, A. Varykhalov, O. Rader, L. M. Schoop
Summary: In this study, the electronic structure of Au2Pb is investigated using angle-resolved photoemission spectroscopy. It is found that Au2Pb exhibits the characteristics of a three-dimensional Dirac semimetal, with the bulk Dirac cone structure undergoing a significant downward shift in binding energy as the temperature decreases, eventually undergoing a Lifshitz transition. These findings not only expand the range of known materials exhibiting three-dimensional Dirac phases, but also demonstrate a possible mechanism for controlling the contribution of the degeneracy point to electron transport without external doping.
PHYSICAL REVIEW LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Subhajit Roychowdhury, Mengyu Yao, Kartik Samanta, Seokjin Bae, Dong Chen, Sailong Ju, Arjun Raghavan, Nitesh Kumar, Procopios Constantinou, Satya N. Guin, Nicholas Clark Plumb, Marisa Romanelli, Horst Borrmann, Maia G. Vergniory, Vladimir N. Strocov, Vidya Madhavan, Chandra Shekhar, Claudia Felser
Summary: In this study, the electronic structure of ferromagnetic EuCd2As2, predicted to be an ideal Weyl semimetal, is investigated using angle-resolved photoemission spectroscopy and scanning tunneling microscopy. The experimental results are in close agreement with the first principles calculations. Furthermore, anomalous Hall conductivity and Nernst effect are observed, resulting from the non-zero Berry curvature and the topological Hall effect arising from changes in the band structure caused by spin canting produced by magnetic fields. These findings provide insights into exotic quantum phenomena in inorganic topological materials with multiple pairs of Weyl nodes.
Article
Nanoscience & Nanotechnology
D. Maryenko, I. V. Maznichenko, S. Ostanin, M. Kawamura, K. S. Takahashi, M. Nakamura, V. K. Dugaev, E. Ya. Sherman, A. Ernst, M. Kawasaki
Summary: The emergence of an interfacial superconducting state in epitaxial heterostructures of LaTiO3 and KTaO3 has been observed, with the superconductivity transition temperature increasing as the thickness of LaTiO3 decreases. This behavior is observed for both (110) and (111) crystal oriented structures. For thick samples, the finite resistance developing below the superconducting transition temperature increases with increasing LaTiO3 thickness. The (001) oriented heterointerface features a high electron mobility of 250 cm(2) V-1 s(-1) and shows no superconducting transition down to 40 mK, consistent with previous reports. Our results suggest a non-trivial impact of LaTiO3 on the superconducting state and demonstrate the possibility of integrating superconducting KTaO3 interfaces with other oxide materials.
Article
Nanoscience & Nanotechnology
Mihovil Bosnar, Alexandra Yu. Vyazovskaya, Evgeniy K. K. Petrov, Evgueni V. V. Chulkov, Mikhail M. M. Otrokov
Summary: Chern insulators are two-dimensional magnetic topological materials that conduct electricity along their edges via one-dimensional chiral modes. We propose an efficient approach for achieving high Chern number states in MnBi2Te4/hBN van der Waals multilayer heterostructures. Our results show that a stack of n MnBi2Te4 films intercalated by hBN monolayers can give rise to a high Chern number state with n chiral edge modes. This state can be achieved both with and without an external magnetic field, resulting in quantized Hall conductance. Our findings pave the way for practical high Chern number quantized Hall systems.
NPJ 2D MATERIALS AND APPLICATIONS
(2023)
Article
Chemistry, Physical
Hyeon Han, Quentin Jacquet, Zhen Jiang, Farheen N. Sayed, Jae-Chun Jeon, Arpit Sharma, Aaron M. Schankler, Arvin Kakekhani, Holger L. Meyerheim, Jucheol Park, Sang Yeol Nam, Kent J. Griffith, Laura Simonelli, Andrew M. Rappe, Clare P. Grey, Stuart S. P. Parkin
Summary: This study successfully demonstrates the epitaxial growth of single-crystalline T-Nb2O5 thin films with vertical 2D channels for fast Li-ion migration. The films exhibit a colossal insulator-metal transition due to the population of previously empty Nb 4d(0) states. In addition, multiple unexplored phase transitions with distinct crystal and electronic structures have been discovered, allowing for reversible and repeatable manipulation of these phases and their unique electronic properties.
Article
Materials Science, Multidisciplinary
Martin Gutierrez-Amigo, Maia G. Vergniory, Ion Errea, J. L. Manes
Summary: Using group theory, topological quantum chemistry, first-principles, and Monte Carlo calculations, we investigate the topology of the 2D buckled honeycomb lattice phonon spectra. We find that there are eleven distinct phases, five of which are guaranteed to have nontrivial topology according to topological quantum chemistry. By adding four more phases identified as topological using Wilson loops in an analytical model, we obtain a total of nine topological phases. However, when we compute the ab initio phonon spectra for Si, Ge, P, As, and Sb in this structure, we find that all of the crystals lie in a trivial phase. Monte Carlo calculations reveal the physical difficulties in realizing topological phonon phases in real materials with this crystal structure.
Article
Materials Science, Multidisciplinary
Sebastian Paischer, Giovanni Vignale, Mikhail I. Katsnelson, Arthur Ernst, Pawel A. Buczek
Summary: We propose an ab initio method that incorporates the interaction of electrons and magnons in ferromagnets for electronic structure calculations. By approximating complex quantities with time-dependent density functional theory quantities, we develop a simple and affordable algorithm that allows for the study of more complex materials while accounting for the nonlocality of the self-energy. This approach also enables straightforward incorporation of self-consistency and demonstrates good agreement with experimental and theoretical findings for iron and nickel. Additionally, we investigate nonquasiparticle states in the band gap of the half-metallic ferromagnet NiMnSb due to spin-flip excitations.
Article
Materials Science, Multidisciplinary
Vipin Vijayan, L. Chotorlishvili, A. Ernst, S. S. P. Parkin, M. I. Katsnelson, S. K. Mishra
Summary: In a two-dimensional helical spin lattice, the presence of a quantum skyrmionic phase is observed. This topological phase remains stable over a large parameter space before transitioning to a ferromagnetic phase. The stability is enhanced and the topological phase is shifted in the parameter space due to the influence of next-nearest-neighbor interaction. Nonanalytic behavior in the rate function indicates a dynamical quantum phase transition when the system undergoes a quench from the quantum skyrmion phase to a trivial quantum ferromagnetic phase, while no dynamical quantum phase transition is observed when the system quenches from the skyrmion phase to a helical phase.
Article
Materials Science, Multidisciplinary
Rohit K. Shukla, Levan Chotorlishvili, Vipin Vijayan, Harshit Verma, Arthur Ernst, Stuart S. P. Parkin, Sunil K. Mishra
Summary: In this study, we propose a concept of a quantum information diode (QID) by exploiting the effect of nonreciprocal magnons in a system with no inversion symmetry. We demonstrate that by applying an external electric field and utilizing a magnonic crystal, we can control and enhance the asymmetric transmission of quantum information, rectifying the flaw of quantum information.
MATERIALS FOR QUANTUM TECHNOLOGY
(2023)
