Article
Materials Science, Multidisciplinary
Pavel Marton, Mauro A. P. Goncalves, Marek Pasciak, Sabine Koerbel, Venceslav Chumchal, Martin Plesinger, Antonin Klic, Jirka Hlinka
Summary: We conducted a theoretical investigation on a charged 180 degrees domain wall in ferroelectric PbTiO3, compensated by randomly distributed immobile charge defects, using atomistic shell-model simulations and continuous phase-field simulations. Our predictions show that the domain walls form a zigzag pattern, accompanied by local polarization rotation, which provides an efficient mechanism for charge compensation.
Article
Chemistry, Multidisciplinary
Cam-Phu Thi Nguyen, Peggy Schoenherr, Jan Seidel
Summary: The functionality of domain walls and other topological defects in ferroelectrics is being extensively studied for applications in electronic devices. This study presents an in-depth investigation of the nanomechanical properties at 90° domain walls and adjacent domains in single-crystalline lead titanate (PbTiO3) using various AFM-based methods. Significant variations in elastic moduli are observed at 90° domain walls, extending up to approximately 100 nm into the domain areas. AFM nanoindentation is also used to measure local domain wall hardness and deformation energies. These findings have implications for the design of ferroelectric domain wall functionality that incorporates the intrinsic elastic compliance of a domain wall.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Physical
Leif D. Jacobson, James M. Stevenson, Farhad Ramezanghorbani, Delaram Ghoreishi, Karl Leswing, Edward D. Harder, Robert Abel
Summary: Transferable high dimensional neural network potentials (HDNNPs) have shown great potential in improving the accuracy and applicability of existing atomistic force fields for organic systems in life science. This study extends the previous work on a potential called Schro''dinger-ANI to cover ionic and zwitterionic druglike molecules relevant to drug discovery. A novel HDNNP architecture called QRNN is introduced, which predicts atomic charges and uses them as descriptors in an energy model to accurately calculate conformational energies. Additionally, delta learning based on a semiempirical level of theory reduces errors by approximately half. The models are tested on various aspects, including torsion energy profiles, conformational energies, geometric parameters, and tautomer errors.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Materials Science, Multidisciplinary
I. Rychetsky, W. Schranz, A. Troester
Summary: This study proposes a new mechanism that leads to a switchable Bloch-type polarization in a domain wall separating two ferroelectric domain states. The mechanism is triggered by the biquadratic coupling of the primary order parameter and its gradient originating from inhomogeneous electrostriction. The study also describes the origin and properties of the polar Bloch component.
Article
Nanoscience & Nanotechnology
Xiaomei He, Xiangdong Ding, Jun Sun, Guillaume F. F. Nataf, Ekhard K. H. Salje
Summary: In this study, molecular dynamics simulations were performed to identify the ridges and valleys with rounded singularities around the intersections between twin walls and surfaces. The two dominant length scales observed were due to the elastic bending of the surface layer and local atomic reshuffles. For static twin walls, the change in Young's modulus involved softening near valleys and hardening near ridges. The boundary-induced changes in the surface Young's modulus were approximately 0.7%.
Article
Nanoscience & Nanotechnology
David Bugallo, Eric Langenberg, Elias Ferreiro-Vila, Eva H. Smith, Christina Stefani, Xavier Batlle, Gustau Catalan, Neus Domingo, Darrell G. Schlom, Francisco Rivadulla
Summary: By analyzing the temperature dependence of the thermal conductivity of a ferroelectric PbTiO3 thin film, this study identified ferroelectric domain walls and point defects as the main sources of phonon scattering. The research demonstrated that domain walls are as effective as point defects in limiting the thermal conductivity in the system.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Materials Science, Multidisciplinary
Yu Pang, Yongheng Li, Ziyan Gao, Xin Qian, Xueyun Wang, Jiawang Hong, Puqing Jiang
Summary: In this study, the thermal conductivity of h-ErMnO3 single crystals with different vortex domain walls (DWs) was investigated using time-domain thermoreflectance (TDTR). It was found that the vortex DWs can effectively suppress the thermal conductivity along and perpendicular to the c-axis of the crystals. A phonon scattering model was used to explain the mechanism of thermal transport manipulated by the vortex DWs. These findings not only provide an essential understanding of heat transport in multiferroics with vortex DWs but also pave the way for their application in next-generation ferroelectric devices.
MATERIALS TODAY PHYSICS
(2023)
Article
Engineering, Electrical & Electronic
Hiroshi Uchimura, Nobuki Hiramatsu, Hiromichi Yoshikawa
Summary: This research focuses on using artificial magnetic conductor (AMC) as a small antenna that maintains its performance on metal surfaces. By introducing electric walls, the size of the AMC was reduced while maintaining its antenna function. This design allows the AMC to function as an antenna by feeding power directly to its patch.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2021)
Article
Astronomy & Astrophysics
Francesco Bigazzi, Aldo L. Cotrone, Andrea Olzi
Summary: When axionic strings carry a global charge, domain walls bounded by such strings may not be allowed to decay completely. This happens in particular in some models where a composite axionlike particle is the pseudo-Nambu-Goldstone boson of chiral symmetry breaking of an extra quark flavor. In this case, the global symmetry is the extra flavor baryonic symmetry. The corresponding axionic domain walls can carry a baryonic charge: they represent the low energy description of the baryons made by the extra quark flavor. Basic properties of these particles, such as spin, mass scale, and size are discussed. The corresponding charged axionic strings are explicitly constructed in a specific calculable model.
Article
Engineering, Mechanical
Yuanqiang Luo, Guangwen Huang, Yi Peng, Zhen Liang, Yugang He
Summary: This paper proposes three specific preparation schemes for wettability-patterned copper surfaces and investigates the influence of preparation conditions on the contact angle. By comparing the effects of different schemes, it is found that preparation scheme 3 has the best effect. The motions and spreading of water droplets on wettability-patterned copper surfaces with four new patterns are observed, and the applicability of preparation scheme 3 for droplet control is verified. Furthermore, this new preparation scheme can be conducted at room temperature without special equipment, and it has the shortest preparation time, making it suitable for batch fabrication.
SURFACE TOPOGRAPHY-METROLOGY AND PROPERTIES
(2022)
Article
Materials Science, Ceramics
Mojca Otonicar, Mirela Dragomir, Tadej Rojac
Summary: This article highlights the importance of domain walls in ferroelectric and relaxor-based oxide ceramics and discusses their impact on material properties. By studying the dynamics of domain walls, insights into the design and application of these materials can be gained.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2022)
Article
Materials Science, Multidisciplinary
Fernando Rubio-Marcos, Paula Pamies, Adolfo Del Campo, Jordi Tiana, Jonathan Ordonez-Pimentel, Michel Venet, Rocio E. Rojas-Hernandez, Diego A. Ochoa, Jose F. Fernandez, Jose E. Garcia
Summary: A clear correlation between optical absorption and light-induced strain in ferroelectrics is shown. The phenomenon of photoinduced electronic reconstruction at charged domain walls is proposed as the primary physical mechanism. These results provide a new pathway for designing ferroelectric-based devices with new functionalities, such as thickness gradient-based photo-controlled nanoactuators.
APPLIED MATERIALS TODAY
(2023)
Article
Astronomy & Astrophysics
Mariano Chernicoff, Gaston Giribet, Emilio Rubin de Celis
Summary: This study examines extremal surfaces in a traversable wormhole geometry and their use in calculating holographic entanglement entropy. It analyzes different configurations to explore the phase transitions in the dual theory.
Article
Biology
Mark D. Allen, Stefan M. Freund, Mark Bycroft, Giovanna Zinzalla
Summary: The crystal structure of the N-terminus of SWI/SNF chromatin remodelling factor subunit BAF155 was determined, revealing an interconnected structure of MarR-like, BRCT, and chromodomains. The study shows potential effects of cancer-associated missense mutations and suggests a binding site and target for small molecule inhibitors, offering a new strategy to target SWI/SNF complexes.
COMMUNICATIONS BIOLOGY
(2021)
Review
Materials Science, Multidisciplinary
Yazhu Dong, Kai Zou, Ruihong Liang, Zhiyong Zhou
Summary: This review comprehensively presents the fundamental principles, progress, and future prospects of BS-PT-based materials, including key issues such as piezoelectric properties, phase diagrams, and temperature stability. Furthermore, the development of BS-PT thin films and single crystals is also discussed.
PROGRESS IN MATERIALS SCIENCE
(2023)
Article
Multidisciplinary Sciences
Le Van Lich, Tinh Quoc Bui, Takahiro Shimada, Takayuki Kitamura, Hue Dang Thi Hong, Trong-Giang Nguyen, Van-Hai Dinh
Summary: A phase field model for nonlinearly graded ferroelectric thin films has been developed based on the Ginzburg-Landau theory. The model has been validated through simulations and comparison with experimental data, showing enhanced electromechanical properties due to controlled gradient index. Furthermore, an increase in energy storage density and charge-discharge efficiency has been observed with higher gradient index of thin films.
ADVANCED THEORY AND SIMULATIONS
(2022)
Article
Chemistry, Multidisciplinary
Takashi Sumigawa, Takahiro Shimada, Kai Huang, Yuki Mizuno, Yohei Hagiwara, Naoki Ozaki, Takayuki Kitamura
Summary: Crystal defects, specifically dislocations, play a crucial role in brittle fracture of materials. This study investigates the fracture mechanism of dislocations in SrTiO3 through atomic-level observations and theoretical evaluations, revealing a lower fracture strength and quantitatively evaluating the fracture toughness of dislocation-induced cracks.
Article
Physics, Applied
Yu Wang, Takayuki Kitamura, Jie Wang, Hiroyuki Hirakata, Takahiro Shimada
Summary: This study demonstrates the effect of mechanical strain on the motion of magnetic skyrmions in a temperature gradient using a phase-field model. The results show that strain-induced anisotropic deformation increases the driving force and accelerates the motion of skyrmions. A kinematic equation is proposed to describe the relationship between skyrmion velocity and multiphysics field variables. The potential application of mechanically controlled skyrmion thermal motion is also demonstrated.
PHYSICAL REVIEW APPLIED
(2022)
Article
Mechanics
Hiroyuki Hirakata, Masao Akiyoshi, Ryoichi Masuda, Takahiro Shimada
Summary: In this study, it was demonstrated that van der Waals-layered MoTe2, with its closely laminated two-dimensional atomic layers through weak interactions, exhibits higher fracture toughness in out-of-plane cracks compared to in-plane cracks due to structural anisotropy. In situ electron microscopy fracture toughness tests showed that the apparent fracture toughness of the out-of-plane crack was approximately twice that of the in-plane crack based on the continuum assumption. As loading progressed in the out-of-plane crack specimen, inter-laminar slip occurred between the layers, and this discrete nature resulted in the disappearance of stress singularity, leading to high fracture toughness.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Physics, Applied
Hiroyuki Hirakata, Shigekazu Homma, Hiroki Noda, Shumpei Sakaguchi, Takahiro Shimada
Summary: This study demonstrates that injecting excess electrons or holes into a material by electron beam irradiation can enhance bond strength. Experimental and computational results show that the increase in fracture toughness is more significant under hole-injection conditions.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Tao Xu, Yuuki Ichiki, Kairi Masuda, Yu Wang, Hiroyuki Hirakata, Takahiro Shimada
Summary: Stable polar skyrmions of about 10 nanometers in size have been recently discovered in complex systems, but their existence is limited to nanoscale due to ferroelectric critical size. This study proposes a strategy to overcome this limitation and achieve ultrasmall and isolated polar skyrmions by introducing excess-electron polarons in nonferroelectric SrTiO3 heterostructures. The results demonstrate that a surface polaron can induce a Neel-type polar skyrmion as small as 1.8 nanometers. The polar topological structure can be tuned by heterostructures and mechanical approaches.
Article
Materials Science, Multidisciplinary
Le Van Lich, Dang Thi Hong Hue, Do Thi Huong Giang, Nguyen Huu Duc, Takahiro Shimada, Takayuki Kitamura, Van-Hai Dinh
Summary: Patterning three-dimensional chiral nanostructures is a new approach to control complex magnetization textures in magnetic systems, leading to new physics and functionalities. However, understanding the geometry-induced effects in magnetic nanostructures remains challenging due to the complex interactions among magnetic interactions, confined geometries, and multi-fields. In this study, we use micromagnetic simulations to investigate the magnetization textures in Ni79Fe21 gyroid nanostructures with different solid volume fractions. Unusual magnetic field textures with the coexistence of left- and right-hand helices are formed in the gyroid nanostructures in the absence of an external field. The ice rule governs the magnetic field textures in gyroids with small solid volume fractions, while a frustration of magnetic textures is observed in gyroids with large solid volume fractions.
Article
Materials Science, Multidisciplinary
Yu Wang, Jie Wang, Takayuki Kitamura, Hiroyuki Hirakata, Takahiro Shimada
Summary: A coherent magnitude wave hidden in spin waves has been discovered, and its coupling with magnetic patterns has been revealed, complementing the understanding of spin waves and offering a new avenue for future research on magnetic dynamics.
Article
Physics, Applied
Qi-Lin Xiong, Takahiro Shimada, Takayuki Kitamura
Summary: In this study, the thermal dissipation induced by a fast-moving edge dislocation is investigated using molecular dynamics simulations. The influence of non-Schmid stress on the thermal dissipation is discussed. It is found that the majority of the energy emitted by the moving dislocation is converted into thermal energy and dissipated, and the thermal dissipation depends significantly on the non-Schmid stress.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Physical
Tao Xu, Jingtong Zhang, Chunyu Wang, Xiaoyuan Wang, Takahiro Shimada, Jie Wang, Hongxin Yang
Summary: Low-dimensional multiferroic metals, characterized by the coexistence of ferroelectricity, conductivity, and magnetism, have great potential for scientific and technological endeavors. In this study, intrinsic one-dimensional ferroelectrics and carrier doping-induced metallic multiferroics are designed and demonstrated in an atomic WOF4 wire. The wire exhibits pronounced ferroelectricity and the ability to sustain a high Curie temperature, while doping with electrons induces magnetism and metallic conductivity in coexistence with ferroelectric distortion.
JOURNAL OF MATERIOMICS
(2023)
Article
Physics, Applied
Susumu Minami, Tomohiro Nakayama, Takahiro Shimada
Summary: In this study, the deformation behavior and tensile strength of ferroelectric ceramics (PbTiO3) under high mechanical loading are investigated using first-principles calculations. It is found that the ceramics exhibit superelastic-like nonlinear deformation with large critical strain. The displacement of oxygen atoms due to the ferroelectric phase transition is identified as the cause of this unique nonlinear deformation. Additionally, the piezoelectric coefficient of the ceramics is calculated, showing a singular peak at inflection points of the stress-strain curve.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Masao Akiyoshi, Takahiro Shimada, Hiroyuki Hirakata
Summary: This study developed a mechanical model that can simulate the bending deformation characteristics of vdW-layered materials while taking into account the microscopic mechanism of interlayer slips. The model was validated through comparisons with experimental results, demonstrating its accuracy and effectiveness.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Tao Xu, Jingtong Zhang, Takahiro Shimada, Jie Wang, Hongxin Yang
Summary: In this study, a new one-dimensional antiferroelectric material, VOF3 atomic wire, is demonstrated based on first-principles and second-principles calculations. The material exhibits phase transitions with temperature and can achieve high energy densities and efficiencies at room temperature.
Article
Multidisciplinary Sciences
Hiroki Noda, Shumpei Sakaguchi, Ryoga Fujita, Susumu Minami, Hiroyuki Hirakata, Takahiro Shimada
Summary: This study investigates the effect of excess electrons/holes on the bonding strength of covalent Si using first-principles density-functional theory calculations. It is found that the bond strength of Si decreases or increases monotonically with the doping concentration, with a maximum change of 30-40% at the highest doping concentration. Furthermore, the change in bond strength is determined by the bonding/antibonding state of the doped excess electrons/holes.
SCIENTIFIC REPORTS
(2023)
Article
Engineering, Mechanical
Tao Xu, Chunyu Wang, Yuquan Zhu, Yu Wang, Yabin Yan, Jie Wang, Takahiro Shimada, Takayuki Kitamura
Summary: This study proposes the concept of temperature-controlled mechanics and demonstrates the design of NiTi alloys with exceptional mechanical properties by combining high-throughput phase-field simulations and machine learning approaches. The nontrivial mechanical properties, including ultra-low modulus, linear superelasticity, and no hysteresis, are achieved through continuous variations in the critical stress for the martensitic transformation. Active learning workflow and the SISSO algorithm are employed to optimize the temperature environment and establish an explicit expression for the Young's modulus, providing guidance for the inverse design of the temperature field. This research not only provides insights into the effects of temperature gradients on martensitic transformations and mechanical properties, but also offers a promising computational approach for developing advanced materials.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
