Article
Chemistry, Multidisciplinary
Lutz Baumgarten, Thomas Szyjka, Terence Mittmann, Andrei Gloskovskii, Christoph Schlueter, Thomas Mikolajick, Uwe Schroeder, Martina Mueller
Summary: The reliability of ferroelectric HfO2- and HZO-based memory devices is strongly influenced by the choice of electrode materials. Interface conditions, such as band alignment, defect formation, and doping, are recognized as decisive factors for device performance. Hard X-ray photoelectron spectroscopy reveals two opposite scenarios of band alignment in TiN/HZO/TiN and IrO2/HZO/IrO2, explaining the conditions for stable device performance and degradation. A key condition for the stability of ferroelectric devices is identified as the alignment of the charge neutrality level with the metallic Fermi level. Oxygen-deficient HfO2-based interfaces, where the Fermi level of the metal electrode is close to the conduction band of the ferroelectric insulator, can achieve stable device performance.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Crystallography
Michal Marek Pilch, Christian Rodenbuecher, Franciszek Krok, Kristof Szot
Summary: Our paper investigates the distribution of dopants in lanthanum-doped strontium titanate (LSTO) single crystals. We found a discrepancy between theoretical and experimental densities. Transmission electron microscopy, energy-dispersive X-ray spectroscopy, and selected area diffraction confirmed that the concentration of lanthanum varies significantly on the micro- and nanoscopic scale. Using local conductivity atomic force microscopy measurements, we observed band-like inhomogeneities in the electrical conductivity, which correlated with the distribution of lanthanum.
Article
Astronomy & Astrophysics
Michela Negro, Henrike Fleischhack, Andreas Zoglauer, Seth Digel, Marco Ajello
Summary: The Fermi Bubbles are a pair of ellipsoidal structures near the Galactic center, and their nature and origin remain unclear. Investigating the emission mechanisms is crucial, and MeV observations provide important clues.
ASTROPHYSICAL JOURNAL
(2022)
Article
Chemistry, Physical
Jacob N. Vagott, Kathryn Bairley, Juanita Hidalgo, Carlo A. R. Perini, Andres-Felipe Castro-Mendez, Sarah Lombardo, Barry Lai, Lihua Zhang, Kim Kisslinger, Josh Kacher, Juan-Pablo Correa-Baena
Summary: Atomic layer deposition (ALD) allows precise control over the thickness, stoichiometry, and structural defects of materials. This study deposited lead iodide (PbI2) using a facile ALD process with readily accessible and low-cost precursors. The deposited PbI2 was characterized using various techniques and lays the foundation for further development of lead halide perovskite processes by ALD.
CHEMISTRY OF MATERIALS
(2022)
Article
Multidisciplinary Sciences
Artur Born, Fredrik O. L. Johansson, Torsten Leitner, Danilo Kuehn, Andreas Lindblad, Nils Martensson, Alexander Foehlisch
Summary: The chemical shift of core level binding energies in ESCA makes it a valuable analytical tool, and the use of APECS allows for experimental detection of these shifts with additional selectivity. Through coincident measurement of specific decay channels, the chemical shifts of Ni 3p levels in a crystal and its oxidized layer have been accurately determined.
SCIENTIFIC REPORTS
(2021)
Article
Multidisciplinary Sciences
J. Niskanen, A. Vladyka, J. Niemi, C. J. Sahle
Summary: In this study, we explore the sensitivity of several core-level spectroscopic methods to the atomistic structure using water molecule as a test system. We define a metric to measure the magnitude of spectral change as a function of structure, which enables us to identify structural regions with high spectral sensitivity. By employing machine-learning emulator-based decomposition of structural parameter space, we are able to recover more spectral variance and identify spectroscopically dominant degrees of freedom.
ROYAL SOCIETY OPEN SCIENCE
(2022)
Article
Chemistry, Physical
Sergei S. Sakhonenkov, Elena O. Filatova
Summary: This study presented an atomic-level investigation on the mixing behavior of W and Be during magnetron sputtering deposition using the SRIM software, showing that kinetic energy is a key factor influencing the formation of beryllides at interfaces during sputtering. Additionally, a complete mixing of layers and formation of specific compounds were observed in multilayer structures.
APPLIED SURFACE SCIENCE
(2022)
Article
Chemistry, Multidisciplinary
Stanislav Cichon, Frantisek Maca, Vaclav Drchal, Katerina Horakova, Irena Kratochvilova, Jan Lancok, Vladimir Chab, Patrik Cermak, Jiri Navratil, Cestmir Drasar
Summary: In this study, a reliable method for preparing high-quality single crystal substrates doped with Bi2Se3 was developed. The electronic properties and chemical states of atoms in the substitutional position and native defects in the topological insulator were analyzed using experimental and theoretical methods. The relationship between the position of the Dirac cone and valence band maximum was explored and discussed.
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
(2024)
Article
Chemistry, Physical
Mindaugas Andrulevicius, Evgenii Artiukh, Gunnar Suchaneck, Sitao Wang, Nikolai A. A. Sobolev, Gerald Gerlach, Asta Tamuleviciene, Brigita Abakeviciene, Sigitas Tamulevicius
Summary: X-ray photoelectron spectroscopy was used to investigate the direct synthesis of strontium and molybdenum oxide thin films by multitarget reactive magnetron sputtering. By varying the power applied to the Mo target, films with different concentrations of Mo atoms were produced. The XPS spectra revealed that both molybdenum and strontium were in the oxidized state, with Mo bonds in a lower valence state and similar Sr spectra for all samples.
Article
Materials Science, Multidisciplinary
G. A. Alna'washi, A. M. Alsmadi, I. Bsoul, B. Salameh, Gassem M. Alzoubi, M. Shatnawi, S. M. Hamasha, S. H. Mahmood
Summary: The substitution of Fe3+ ions with a combination of Ni2+ and Ti4+ in SrM hexaferrites synthesized via mechanical ball-milling technique was investigated. XRD and XPS confirmed the phase purity and elemental distribution, respectively. The study revealed electron transfers between Fe3+ and Ni2+ ions with increasing Ni concentration, leading to changes in magnetic behavior and anisotropy constants.
RESULTS IN PHYSICS
(2021)
Article
Chemistry, Physical
R. E. Asfin, S. M. Melikova, A. V. Domanskaya, K. S. Rutkowski, D. N. Shchepkin
Summary: The IR spectra of CDF3 in solid Ar and N-2 matrices were analyzed in the region of the Fermi polyads, and the effects of Fermi resonance were observed. The theoretical calculations of the potential energy surface and dipole moment function were performed, and the experimental findings were in good agreement with the theoretical analysis.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Risi Guo, Xiulan Xu, Yan Ma, Gang Han, Lihua Wang, Jiao Teng, Guanghua Yu
Summary: In this study, MgO layer was prepared using two different methods. It was found that one method resulted in a sample with in-plane magnetic anisotropy, while the other method resulted in a sample with perpendicular magnetic anisotropy. XPS results showed that when the annealing temperature was below 300°C, the composition ratio of the interface was in the range of 0.65-0.75, and the sample exhibited perpendicular magnetic anisotropy.
APPLIED SURFACE SCIENCE
(2022)
Article
Chemistry, Physical
A. Pancotti, J. J. Silva, A. de Siervo, R. Landers, P. A. P. Nascente
Summary: The surface composition of a (root 5 x root 5)-R26.6 degrees reconstruction of a strontium titanate (001) single crystal was characterized by X-ray photoelectron spectroscopy, while its atomic surface structure was determined by a combination of low energy electron diffraction and X-ray photoelectron diffraction. Experimental and theoretical XPD results suggested that the surface reconstruction has two possible terminations: 40% SrO and 60% TiO2.
Article
Chemistry, Multidisciplinary
Jiarong Zhang, Long Chen, Xing Dai, Lixi Chen, Fuwan Zhai, Weifeng Yu, Shikai Guo, Lijiang Yang, Lanhua Chen, Yugang Zhang, Linwei He, Changlun Chen, Zhifang Chai, Shuao Wang
Summary: This study demonstrates the potential application of ultrastable crystalline zirconium phosphonate framework (SZ-7) for efficient removal of strontium under highly alkaline conditions, with high adsorption capacity and in-depth removal performance, offering a new solution for Sr-90 removal in highly alkaline nuclear waste.
CHEMICAL COMMUNICATIONS
(2021)
Article
Chemistry, Physical
Maxim K. Rabchinskii, Svyatoslav D. Saveliev, Dina Yu. Stolyarova, Maria Brzhezinskaya, Demid A. Kirilenko, Marina Baidakova, Sergei A. Ryzhkov, Vladimir V. Shnitov, Victor V. Sysoev, Pavel N. Brunkov
Summary: This study demonstrates the modulation of N species by tailoring the functionalization and atomic structure of graphene derivatives prior to chemical N-doping. Thermal annealing at moderate temperatures was shown to readjust the composition of N-species in graphene derivatives regardless of their chemistry, nanostructure, and the initial distribution of the N-species. The oxidation of the graphene layer governs the manifestation of pi* resonances and configuration of sigma* resonance.
Article
Chemistry, Physical
Shishin Mo, Tsukasa Katayama, Akira Chikamatsu, Miho Kitamura, Koji Horiba, Hiroshi Kumigashira, Tetsuya Hasegawa
Summary: By applying 0.5% tensile strain to c-axis-oriented Mn2Mo3O8 epitaxial films, a significant increase in spontaneous magnetization was observed, leading to a noncollinear spin structure with tilted Mn2+ magnetic moments compared to the bulk material. The study suggests that the direction of the Mn2+ magnetic moment is sensitive to tensile strain, indicating a potential for manipulating magnetic properties in thin films.
CHEMISTRY OF MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
Kaidong Wang, Kazunori Nishio, Koji Horiba, Miho Kitamura, Kurei Edamura, Daisuke Imazeki, Ryo Nakayama, Ryota Shimizu, Hiroshi Kumigashira, Taro Hitosugi
Summary: In this paper, the synthesis of high-entropy oxide thin films with a layered rocksalt structure was reported using the pulsed laser deposition technique. The successful preparation of LiCr1/6Mn1/6Fe1/6Co1/6Ni1/6Cu1/6O2 thin films with a layered rocksalt structure was achieved by tuning the laser fluence and substrate temperature. Additionally, a thin-film-type solid-state battery was fabricated with the epitaxial thin film as a positive electrode, demonstrating stable operation.
CRYSTAL GROWTH & DESIGN
(2022)
Article
Chemistry, Multidisciplinary
Kohei Yoshimatsu, Hiroshi Kumigashira
Summary: High-quality metastable lambda-phase trititanium pentoxide (λ-Ti3O5) films were grown at very high temperatures via pulsed-laser deposition, directly on the substrate surface without transient layers. The monoclinic lambda-Ti3O5 films obtained were nearly single-domain with less than 1% rotational domains on pseudocubic LaAlO3 substrates. The successful synthesis of these films enables the utilization of their rich functionalities.
CRYSTAL GROWTH & DESIGN
(2022)
Article
Physics, Multidisciplinary
Daiki Ootsuki, Ayuko Hishikawa, Tatsuhiro Ishida, Daisuke Shibata, Yukie Takasuka, Miho Kitamura, Koji Horiba, Yasumasa Takagi, Akira Yasui, Chanchal Sow, Shingo Yonezawa, Yoshiteru Maeno, Teppei Yoshida
Summary: We report the electronic structure of Ca2-xSrxRuO4 (CSRO) for x = 0.06 using angle-resolved photoemission spectroscopy (ARPES) and hard x-ray photoemission spectroscopy (HAXPES). The results show the presence of surface metallic state even in the low temperature bulk insulating phase. The observed band dispersion suggests strong electron-phonon coupling.
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2022)
Article
Physics, Applied
Keisuke Ide, Naoto Watanabe, Takayoshi Katase, Masato Sasase, Junghwan Kim, Shigenori Ueda, Koji Horiba, Hiroshi Kumigashira, Hidenori Hiramatsu, Hideo Hosono, Toshio Kamiya
Summary: In this study, LEDs were fabricated on glass substrates using amorphous oxide semiconductor materials as emission layers. Rare-earth-doped AOS films were employed, and the LEDs emitted clear red, green, and pink luminescence even in the ambient environment. Resonance photoelectron spectroscopy revealed different emission mechanisms for each rare-earth dopant. This study provides opportunities for the advancement of flexible display technologies in harsh environments.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Daisuke Asakura, Eiji Hosono, Miho Kitamura, Koji Horiba, Eisuke Magome, Hiroyuki Setoyama, Eiichi Kobayashi, Hayato Yuzawa, Takuji Ohigashi, Takaaki Sakai, Ryoichi Kanega, Takashi Funaki, Yukari Sato, Akihiro Ohira
Summary: In this study, X-ray absorption spectroscopy was used to investigate the electrolytes of a Ti-Mn redox flow battery, aiming to understand the redox reaction and precipitation formation. The results showed that the valence state of manganese in the precipitates is mostly 4+, while the solution only contains Mn2+.
CHEMISTRY-AN ASIAN JOURNAL
(2023)
Article
Physics, Multidisciplinary
Takemi Kato, Yongkai Li, Kosuke Nakayama, Zhiwei Wang, Seigo Souma, Fumihiko Matsui, Miho Kitamura, Koji Horiba, Hiroshi Kumigashira, Takashi Takahashi, Yugui Yao, Takafumi Sato
Summary: The study found that Nb substitution can increase the superconducting transition temperature and reduce the CDW temperature in Cs(V1-xNbx)(3)Sb-5. Nb substitution adjusts the position of the bands in the band structure, resulting in a decrease in the CDW gap and T-CDW. This study reveals the important role of the SP density of states in stabilizing the CDW, and suggests that the enhancement of superconductivity by Nb substitution is achieved through the expansion of the electron pocket and the recovery of the density of states at the Fermi level.
PHYSICAL REVIEW LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Tatsuhiko Kanda, Daisuke Shiga, Asato Wada, Ryotaro Hayasaka, Yuuki Masutake, Naoto Hasegawa, Miho Kitamura, Kohei Yoshimatsu, Hiroshi Kumigashira
Summary: Quantized states in strongly correlated oxide nanostructures are crucial for designing quantum devices in future electronics. In situ ARPES measurements in SrTi1-xVxO3 reveal that the electron mean free path is a key parameter for controlling and designing quantized states in these structures.
COMMUNICATIONS MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
D. Shiga, X. Cheng, T. T. Kim, T. Kanda, N. Hasegawa, M. Kitamura, K. Yoshimatsu, H. Kumigashira
Summary: Through in situ photoemission spectroscopy, the changes in the electronic structure of Cr-doped VO2 films on TiO2 substrates were investigated. The phase diagram of CrxV1-xO2 was obtained, showing the influence of strain effect on the metal-insulator transition temperature. The spectroscopic investigations revealed the changes in energy gap and V 3d states, as well as the existence of Mott insulating phase without V-V dimerization at high doping concentration.
Article
Materials Science, Multidisciplinary
K. Yoshimatsu, S. Miyazaki, N. Hasegawa, H. Kumigashira
Summary: In this study, we successfully synthesized Ti2O3 epitaxial films with different c/a ratios by changing the growth temperature. We found that the critical c/a ratio for the metal-insulator transition at room temperature is 2.68, which was also confirmed by density functional theory calculations. These results suggest that the transition in Ti2O3 is a gradual semimetal-to-semiconductor transition induced by lattice deformation.
Article
Materials Science, Multidisciplinary
Naoto Hasegawa, Kohei Yoshimatsu, Daisuke Shiga, Tatsuhiko Kanda, Satoru Miyazaki, Miho Kitamura, Koji Horiba, Hiroshi Kumigashira
Summary: Ti2O3 exhibits a unique metal-insulator transition accompanied by lattice deformation. Electron-electron correlation plays an important role in its electronic structure and transition process. The electronic band structure of insulating Ti2O3 films with slight hole doping is obtained using ARPES.
Article
Materials Science, Multidisciplinary
Takuto Soma, Kohei Yoshimatsu, Koji Horiba, Hiroshi Kumigashira, Akira Ohtomo
Summary: The oxide superconductor Li1-xNbO2, with two-dimensional NbO2 layers, exhibits 2D superconductivity and large anisotropy in the upper critical field. The temperature-independent anisotropy suggests single-band superconductivity, which is different from other materials with similar structures. The study also reveals a narrow and correlated single band in the 2D NbO2 layers of Li1-xNbO2, similar to the superconductivity in cuprates.
Article
Materials Science, Multidisciplinary
T. Mizutani, S. Tanaka, T. Saze, K. Fujii, H. Matsuoka, M. Nakano, H. Wadati, M. Kitamura, K. Horiba, Y. Iwasa, H. Kumigashira, M. Yoshiki, M. Taguchi
Summary: Total reflection hard x-ray photoelectron spectroscopy (TR-HAXPES) is a versatile method that can elucidate differences between surface and bulk electronic states of strongly correlated electron systems. By studying the incident angle dependence, it is possible to measure both surface and bulk electronic states without making changes to the experimental setup.
Article
Chemistry, Multidisciplinary
Kohei Yoshimatsu, Hiroshi Kumigashira
Summary: High-quality metastable lambda-phase trititanium pentoxide films were successfully grown on substrates via pulsed-laser deposition at very high growth temperature. These films directly formed on substrates without any detectable transient layers, containing almost single domains with very low fraction of rotational domains. The successful synthesis of these metastable films enables the utilization of their rich functionalities.
CRYSTAL GROWTH & DESIGN
(2022)
