Article
Materials Science, Multidisciplinary
Julien Varignon, Oleksandr I. Malyi, Alex Zunger
Summary: In addition to crystal symmetry and orbital character, the band gaps of d-electron perovskites also depend on the magnetic spin configuration, particularly the nature of the band edge orbital character (BEOC) and the number of antiferromagnetic contacts between neighboring transition metal ions. These dependence rules are traced to the interorbital interactions and play a significant role in understanding phenomena related to band gaps.
Article
Nanoscience & Nanotechnology
Dan Ouyang, Cong Chen, Zhanfeng Huang, Lu Zhu, Yanfa Yan, Wallace C. H. Choy
Summary: This study demonstrates a new hybrid three-dimensional nanostructure system as an efficient hole transport layer in solar cells, achieving nearly 20% power conversion efficiency. By integrating high-conductive chromium-doped CuGaO2 nanoplates into ultrasmall NiOx nanoparticles, the system exhibits advantages such as smooth surface, remarkable charge collection efficiency, and energy level alignment with the perovskite layer.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Acoustics
Nikos Aravantinos-Zafiris, Frieder Lucklum, Mihail M. Sigalas
Summary: This work presents the theoretical and experimental verification of complete phononic band gaps in the Yablonovite structure with additional spheres in a face-centered cubic arrangement. Different spatial directions and polarizations were numerically and experimentally investigated to calculate the phononic band gaps in the acoustic band structure and transmission spectrum. The theoretical findings were confirmed by experimental measurements of 3D-printed prototype samples, showing good agreement and validation of complete phononic band gaps in these structures.
Article
Engineering, Mechanical
Ke Ma, Heedong Goh, Loukas F. Kallivokas
Summary: We discuss a comprehensive process for designing the material properties of three-dimensional periodic structures that exhibit user-defined omnidirectional band gaps. The process involves an inverse medium approach, forcing the vanishing of trial group velocities at the target band gap frequencies to achieve the desired properties. Numerical examples for acoustic metamaterials and metasurfaces demonstrate the methodology.
EXTREME MECHANICS LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Xi Yan, Friederike Wrobel, I-Cheng Tung, Hua Zhou, Hawoong Hong, Fanny Rodolakis, Anand Bhattacharya, Jessica L. McChesney, Dillon D. Fong
Summary: In this study, the atomic and electronic structures of the SrTiO3 (001) surface were monitored using in situ techniques. It was observed that a 2D electron gas (2DEG) disappears and reappears after the completion of each SrO and TiO2 monolayer, respectively. The presence of a TiO2 double layer and vacancies within the layer contribute to the generation of a surface potential and mobile electrons, explaining this phenomenon. This finding provides insights into the complex oxide interfaces and facilitates atomic-scale defect engineering in oxide electronics.
ADVANCED MATERIALS
(2022)
Article
Materials Science, Ceramics
Haiying Liu, Jianguang Feng, Lifeng Dong
Summary: Traditional trial and error methods are inefficient when dealing with a large number of candidates, but machine learning can rapidly discover functional materials and reveal the relationship between structures and properties. In this study, a machine learning model was developed to predict the band gaps of double perovskite oxide (DPO) materials for solar cells, resulting in the screening of 236 promising DPOs with suitable band gaps. The developed model showed excellent predictive performance and confirmed previous research findings through statistical analysis.
CERAMICS INTERNATIONAL
(2022)
Article
Multidisciplinary Sciences
Renxing Lin, Yurui Wang, Qianwen Lu, Beibei Tang, Jiayi Li, Han Gao, Yuan Gao, Hongjiang Li, Changzeng Ding, Jin Wen, Pu Wu, Chenshuaiyu Liu, Siyang Zhao, Ke Xiao, Zhou Liu, Changqi Ma, Yu Deng, Ludong Li, Fengjia Fan, Hairen Tan
Summary: All-perovskite tandem solar cells with an immiscible 3D/3D bilayer heterojunction achieve a record-high PCE of 28% and retain over 90% of their initial performance after 600 hours of continuous operation.
Article
Chemistry, Physical
Jie He, Xuandong Wang, Shenyu Lan, Hengcong Tao, Xinzhi Luo, Yingtang Zhou, Mingshan Zhu
Summary: In this study, a new method using piezoelectric polarization is reported to achieve durable and efficient CO2 reduction activity of various perovskite oxides. By introducing vibration energy, the redox potential of CO2 reduction and a piezoelectric field for CO2 adsorption and activation are established. This method breaks the limitation of intrinsic redox properties of perovskite oxides and allows for high productivity of CO2 conversion.
APPLIED CATALYSIS B-ENVIRONMENTAL
(2022)
Article
Chemistry, Analytical
Jiaxi Hu, Lichun Zhang, Hongjie Song, Yi Lv
Summary: The study presents a rapid and cost-effective methodology for evaluating band gaps of semiconductors through cataluminescence signal, which can serve as an innovative alternative to traditional band gap assessment methods.
ANALYTICAL CHEMISTRY
(2021)
Review
Chemistry, Multidisciplinary
Md Arafat Mahmud, The Duong, Jun Peng, Yiliang Wu, Heping Shen, Daniel Walter, Hieu T. Nguyen, Naeimeh Mozaffari, Grace Dansoa Tabi, Kylie R. Catchpole, Klaus J. Weber, Thomas P. White
Summary: The mixed-dimensional 2D-3D perovskite solar cells, incorporating long carbon-chain organic spacer cations, have shown promising results in terms of enhancing both device efficiency and stability. By carefully balancing the composition of 2D and 3D perovskite, researchers aim to take advantage of the specific properties of each material phase for further improvement.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Chemistry, Physical
XinYu Gao, Huan Liu, Yong Wang, JiaHui Guo, XingWei Sun, WeiYan Sun, Haitao Zhao, Jie Bai, ChunPing Li
Summary: Modulating the d-band electronic structure of LaMn0.3Co0.7O3-δ perovskite nanofibers enhances oxygen electrocatalysis for Zn-Air batteries.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2023)
Article
Chemistry, Inorganic & Nuclear
Masashi Nakamura, Hirofumi Akamatsu, Kotaro Fujii, Yusuke Nambu, Yoichi Ikeda, Tomoki Kanazawa, Shunsuke Nozawa, Masatomo Yashima, Katsuro Hayashi, Kazuhiko Maeda
Summary: The study reveals that H-doped ASn0.7Y0.3O3-delta have almost identical bandgaps regardless of the A-site cation. Appropriate preparation conditions are essential for obtaining H-doped products with low defect densities.
INORGANIC CHEMISTRY
(2022)
Article
Materials Science, Multidisciplinary
Genya Uzurano, Nao Kuwahara, Tomoki Saito, Akihiko Fujii, Masanori Ozaki
Summary: This study demonstrates a universal strategy to improve the stability of perovskite solar cells by controlling the orientation of 2D perovskite on 3D perovskite, overcoming the trade-off between stability and PCE in 2D/3D heterostructure. The orientation angle of 2D perovskite strongly depends on the predominant crystal orientation of the 3D perovskite template.
ACS MATERIALS LETTERS
(2022)
Article
Chemistry, Physical
Yuichi Okazaki, Yushi Fujita, Hidenobu Murata, Naoki Masuyama, Yusuke Nojima, Hidekazu Ikeno, Shunsuke Yagi, Ikuya Yamada
Summary: This study achieved the fast and efficient design of perovskites with high OER catalytic activity using Bayesian optimization, revealing the relationship between chemical compositions and catalytic activities, as well as discovering the promoting effect of non-active elements on catalytic activities.
CHEMISTRY OF MATERIALS
(2022)
Article
Physics, Condensed Matter
Calvin Ku, Patrick H-L Sit
Summary: In this study, oxidation-state constrained density functional theory (OS-CDFT) was used to calculate the optical band gaps of transition metal oxides and dopant state energies in doped anatase. This approach allows for the control of electron transfer and the identification of the transition responsible for the reduced band gap in doped systems.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2021)
Article
Chemistry, Multidisciplinary
Srijani Mallik, Gerbold C. Menard, Guilhem Saiz, Ildar Gilmutdinov, David Vignolles, Cyril Proust, Alexandre Gloter, Nicolas Bergeal, Marc Gabay, Manuel Bibes
Summary: A study has found a large linear magnetoresistance in a SrTiO3 two-dimensional electron gas, which is caused by nanoscale inhomogeneities and revealed by interference between helicoidal electron trajectories, determining the thickness of 2DEG. These results deepen our understanding of the origin of linear magnetoresistance in quantum materials and open up exciting possibilities for exploring the interaction of linear MR with features like Rashba spin-orbit coupling.
Review
Nanoscience & Nanotechnology
Felix Trier, Paul Noel, Joo-Von Kim, Jean-Philippe Attane, Laurent Vila, Manuel Bibes
Summary: Oxide materials exhibit a wide range of functional properties, where electron correlations and spin-orbit coupling play significant roles. Recent advances in oxide spin-orbitronics have led to the realization of exotic phenomena and new functionalities for spintronics applications. The future prospects for this field involve further exploration of spin-charge interconversion, topological spin textures, and the influence of ferroelectricity on spin-orbit-driven effects.
NATURE REVIEWS MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Victor Haspot, Paul Noel, Jean-Philippe Attane, Laurent Vila, Manuel Bibes, Abdelmadjid Anane, Agnes Barthelemy
Summary: This paper analyzes the temperature and thickness dependence of damping in epitaxial thin La0.7Sr0.3MnO3 films, and reveals that the damping involves resistive and conductive contributions, along with the presence of a dead layer affecting the linewidth of ferromagnetic resonance spectra.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
Jin Hong Lee, Lourdes Marcano, Raphael Aeschlimann, Mohamad-Assaad Mawass, Chen Luo, Alexandre Gloter, Julien Varignon, Florin Radu, Sergio Valencia, Manuel Bibes
Summary: Epitaxial strain is applied to orthorhombic chromites to engineer their physical properties, particularly their antiferromagnetic spin order, which is strongly tunable by the applied strain. The orthorhombic chromites exhibit a higher dimensionless figure of merit compared to other perovskites, suggesting their potential use in energy-efficient piezo-spintronic devices.
Article
Multidisciplinary Sciences
Sara Varotto, Annika Johansson, Boerge Goebel, Luis M. Vicente-Arche, Srijani Mallik, Julien Brehin, Raphael Salazar, Francois Bertran, Patrick Le Fevre, Nicolas Bergeal, Julien Rault, Ingrid Mertig, Manuel Bibes
Summary: Rashba interfaces have shown potential as platforms for spin-charge interconversion. We used angle resolved photoemission spectroscopy to investigate KTaO3 two-dimensional electron gases and observed their Rashba-split bands. Our calculations revealed complex spin and orbital textures, as well as interconversion efficiencies exceeding those of other oxide two-dimensional electron gases.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Alexis Jouan, Simon Hurand, Gyanendra Singh, Edouard Lesne, Agnes Barthelemy, Manuel Bibes, Christian Ulysse, Guilhem Saiz, Cheryl Feuillet-Palma, Jerome Lesueur, Nicolas Bergeal
Summary: This study elaborates on a generic scenario for the superconducting phase diagram of SrTiO3-based interfaces. The optimal doping point of maximum critical temperature (Tc) is attributed to the transition between different superconducting states. The dependence of Tc on carrier density exhibits a bifurcation phenomenon, which can be controlled by the details of the doping execution. Different doping methods result in different filling behaviors and superconducting states, providing a generic explanation for the dome-shaped superconducting phase diagram.
ADVANCED MATERIALS INTERFACES
(2022)
Article
Chemistry, Multidisciplinary
Raphael Salazar, Sara Varotto, Celine Vergnaud, Vincent Garcia, Stephane Fusil, Julien Chaste, Thomas Maroutian, Alain Marty, Frederic Bonell, Debora Pierucci, Abdelkarim Ouerghi, Francois Bertran, Patrick Le Fevre, Matthieu Jamet, Manuel Bibes, Julien Rault
Summary: Multilayers based on quantum materials have the potential to revolutionize microelectronics and optoelectronics. However, heterostructures incorporating quantum materials from different families remain scarce. In this study, we demonstrate the large-scale integration of compounds from two highly multifunctional families, perovskite oxides and transition-metal dichalcogenides, opening up new possibilities for manipulating the properties of transition-metal dichalcogenides through proximity effects.
Article
Physics, Multidisciplinary
Julien Brehin, Yu Chen, Maria D'Antuono, Sara Varotto, Daniela Stornaiuolo, Cinthia Piamonteze, Julien Varignon, Marco Salluzzo, Manuel Bibes
Summary: This study demonstrates the coexistence of ferroelectricity and magnetism in an oxide-based two-dimensional electron gas, and reveals the magnetoelectric coupling effect. These findings provide new opportunities in the interplay between ferroelectricity, ferromagnetism, metallicity, and Rashba spin-orbit coupling.
Article
Chemistry, Physical
Julien Varignon
Summary: The recent discovery of nickel oxide superconductors highlights the importance of first-principles simulations in understanding the formation of bound electrons in superconductivity. However, density functional theory (DFT) cannot properly account for the strong electronic correlation effects in oxides, disqualifying this technique. Sr1-xKxBiO3 superconductors, being isostructural to nickel oxides, provide an ideal platform for studying complex superconductors and the underlying pairing mechanism. This study shows that parameter-free DFT simulations can accurately capture the experimental features and quantities of Sr1-xKxBiO3 superconductors, including the prediction of a phase transition and the electron-phonon coupling constant in agreement with experiments.
NPJ COMPUTATIONAL MATERIALS
(2023)
Article
Multidisciplinary Sciences
Sara Passuti, Julien Varignon, Adrian David, Philippe Boullay
Summary: Accurate structure analysis of epitaxial perovskite thin films is achieved through Scanning Precession Electron Tomography (SPET), which combines PEDT with area scanning to extract intensity information and refine the structure. The SPET experiment successfully detects small changes in the structure of a 35 nm thick perovskite film, showcasing its potential as a standard procedure for accurate structure analysis of ROIs as small as 10 nm.
Article
Materials Science, Multidisciplinary
Alvaro Adrian Carrasco Alvarez, Manuel Bibes, Wilfrid Prellier, Julien Varignon
Summary: Density functional theory (DFT) is a main tool for studying the electronic structure, but suffers from the self-interaction error (SIE) which causes delocalization errors and metal predictions instead of insulators. The recently developed SCAN functional is successful for 3d transition metal oxides, but fails in describing materials involving more localized states like 4 f orbitals. Insufficiently amended SIEs in SCAN result in an underestimation of Hund's splitting for 4 f states. Therefore, SCAN is not sufficient for studying electronic properties of materials involving rare-earth elements.
Article
Materials Science, Multidisciplinary
Julien Varignon, Oleksandr I. Malyi, Alex Zunger
Summary: In addition to crystal symmetry and orbital character, the band gaps of d-electron perovskites also depend on the magnetic spin configuration, particularly the nature of the band edge orbital character (BEOC) and the number of antiferromagnetic contacts between neighboring transition metal ions. These dependence rules are traced to the interorbital interactions and play a significant role in understanding phenomena related to band gaps.
Article
Physics, Multidisciplinary
Xiangyu Cao, Jie-Xiang Yu, Pengliang Leng, Changjiang Yi, Xiaoyang Chen, Yunkun Yang, Shanshan Liu, Lingyao Kong, Zihan Li, Xiang Dong, Youguo Shi, Manuel Bibes, Rui Peng, Jiadong Zang, Faxian Xiu
Summary: The research discovered that a giant nonlinear anomalous Hall effect can be induced by magnetic-field-induced Lifshitz transitions in the spin-dependent band structure of EuCd2As2. These results not only provide an ideal platform for Berry curvature engineering but also reveal a general effect that may be applicable to other material systems.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Physics, Multidisciplinary
Alvaro Adrian Carrasco Alvarez, Sebastian Petit, Lucia Iglesias, Wilfrid Prellier, Manuel Bibes, Julien Varignon
Summary: This study reveals that rare-earth nickelates are prone to group rotations, which can be easily tuned by external stimuli. H intercalation is favored and promotes the tendency of octahedral rotations.
PHYSICAL REVIEW RESEARCH
(2022)