Article
Materials Science, Multidisciplinary
Manali Vivek, Jacek Goniakowski, Andres Santander-Syro, Marc Gabay
Summary: Angle-resolved photoemission spectroscopy experiments have revealed the presence of a nanometer-thin two-dimensional electron system (2DES) on the (001)-oriented surface of CaTiO3, despite being a band insulator. Our ab initio study indicates that oxygen defects drive the metallicity, while tiltings and rotations of the oxygen octahedra significantly influence the electronic structure and response to external strain deformations of the 2DES. The conduction subbands near the center of the Brillouin zone exhibit a mixed t2g-eg orbital character. TiO2 surface divacancy configurations agree well with experimental spectra.
Article
Multidisciplinary Sciences
Adeel Y. Abid, Yuanwei Sun, Xu Hou, Congbing Tan, Xiangli Zhong, Ruixue Zhu, Haoyun Chen, Ke Qu, Yuehui Li, Mei Wu, Jingmin Zhang, Jinbin Wang, Kaihui Liu, Xuedong Bai, Dapeng Yu, Xiaoping Ouyang, Jie Wang, Jiangyu Li, Peng Gao
Summary: This study successfully uncovered previously unrecognized polar antivortices in SrTiO3 within PbTiO3/SrTiO3 superlattices, expanding the understanding of topological structures. It was revealed that the driving force for antivortex formation is electrostatic rather than elastic, demonstrating potentially significant implications for the manipulation of polar textures.
NATURE COMMUNICATIONS
(2021)
Article
Materials Science, Multidisciplinary
I. Levin, M. G. Han, H. Y. Playford, V. Krayzman, Yimei Zhu, R. A. Maier
Summary: BaZrO3 undergoes a structural change below 80 K, involving correlated out of phase rotations of [ZrO6] octahedra. Electron diffraction reveals superlattice reflections associated with octahedral tilting, while neutron scattering confirms the presence of these rotations.
Article
Materials Science, Multidisciplinary
Alexander Hampel, Jeremy Lee-Hand, Antoine Georges, Cyrus E. Dreyer
Summary: The study shows that the DFT + U method overestimates the inclination towards magnetic ordering and octahedral rotations, resulting in a different ground-state structure. Structural distortions are highly sensitive to electronic correlation effects and the considered magnetic state, even in moderately correlated metals. The robustness of the DFT + DMFT method in obtaining structural properties is demonstrated by comparing different downfolding schemes.
Article
Chemistry, Multidisciplinary
Binbin Chen, Nicolas Gauquelin, Robert J. Green, Jin Hong Lee, Cinthia Piamonteze, Matjaz Spreitzer, Daen Jannis, Johan Verbeeck, Manuel Bibes, Mark Huijben, Guus Rijnders, Gertjan Koster
Summary: By controlling the thickness of NdNiO3 layers in superlattices, the metal-insulator transition (MIT) in correlated oxides can be studied and oxide functionalities can be controlled. The results demonstrate the importance of reducing dimensions in manipulating oxide properties.
Article
Materials Science, Multidisciplinary
Fernando Gomez-Ortiz, Hugo Aramberri, Juan M. Lopez, Pablo Garcia-Fernandez, Jorge iniguez, Javier Junquera
Summary: We report second-principles simulations on domains in (PbTiO3)n/(SrTiO3)n superlattices, finding that for certain thickness and lateral sizes the most stable configuration consists of polar domains separated by counter-rotating vortices acting as domain walls. The balance between domain wall energy and electrostatic energy results in an optimal domain period proportional to the square root of the PbTiO3 layer thickness, following the Kittel law. Molecular dynamics simulations reveal the spontaneous change of periodicity at finite temperature, leading to the formation of new domains initiated by vortices and antivortices.
Article
Materials Science, Multidisciplinary
Fernando Gomez-Ortiz, Pablo Garcia-Fernandez, Juan M. Lopez, Javier Junquera
Summary: We investigated the emergence of Berezinskii-Kosterlitz-Thouless (BKT) phases in (PbTiO3)3/(SrTiO3)3 superlattices using second-principles simulations. Under a tensile epitaxial strain of e = 0.25-1%, the local dipole moments within the superlattices are confined to the film-plane, leading to two-dimensional polarization. Our analysis of dipole-dipole correlation decay, density of defects, and temperature dependence supports the existence of a BKT phase, characterized by quasi-long-range order and the presence of tightly bound vortex-antivortex pairs. This proposed superlattice model can be experimentally verified due to its feasibility in fabrication and the imposed mechanical boundary conditions.
Article
Chemistry, Multidisciplinary
Simin Yin, Shun Liu, Yongfeng Yuan, Shaoyi Guo, Zhaohui Ren
Summary: Octahedral shaped PbTiO3-TiO2 nanocomposites were successfully synthesized in this study, with an increased loading of TiO2 leading to a higher H-2 evolution rate, reaching up to 630.51 mu mol/h, which was 36 times higher than that of the octahedron substrate. The enhanced photocatalytic reactivity of the nanocomposites is attributed to the UV light absorption of the nanooctahedral substrates, efficient separation of photo-generated carriers via the interface and the reaction on the surface of the TiO2 nanocrystals.
Article
Chemistry, Multidisciplinary
Sujit Das, Margaret R. McCarter, Fernando Gomez-Ortiz, Yun-Long Tang, Zijian Hong, Anirban Ghosh, Padraic Shafer, Pablo Garcia-Fernandez, Javier Junquera, Lane W. W. Martin, Ramamoorthy Ramesh
Summary: Nontrivial polarization textures, including ferroelectric domains and vortex structure, have been observed in ferroelectric/dielectric superlattices. By controlling the epitaxial strain, researchers have achieved single-phase vortex structures in superlattices. The thickness of the ferroelectric layer has been found to affect the helicity and chirality of the vortex structures.
Article
Nanoscience & Nanotechnology
Christopher Addiego, Jacob A. Zorn, Wenpei Gao, Sujit Das, Jiaqi Guo, Chengqing Qu, Liming Zhao, Lane W. Martin, Ramamoorthy Ramesh, Long-Qing Chen, Xiaoqing Pan
Summary: In ferroelectric heterostructures, the interaction between intrinsic polarization and the electric field creates various localized electrical properties. The local electric field is influenced by factors such as the charge distribution of individual unit cells, interfacial electromechanical boundary conditions, and chemical composition of the interfaces. However, a complete understanding of the local electric field at micro-, nano-, and atomic-length scales is still lacking, especially in ferroelectric perovskites. In this study, four-dimensional scanning transmission electron microscopy (4D STEM) with multiple probe sizes was used to directly visualize the electric field of polarization vortices in (PbTiO3)(16)/(SrTiO3)(16) superlattices, revealing different electric field configurations corresponding to atomic-scale electronic ordering and nanoscale boundary conditions. The separability of these two fields probed by 4D STEM presents an opportunity to understand the contributions of each to the electronic properties of the film.
Article
Chemistry, Physical
Si-Rui Zhang, Mei-Xiong Zhu, Jagadeesh Suriyaprakash, Jin-Mei Liu, Tao Du, Yu-Jia Wang, Chang-Bai Long, Min Liao
Summary: The study reveals that different flux-closure domain structures can be easily created by controlling the thickness ratio of the bottom and top films. This finding opens up possibilities for creating and constructing novel nanoscale ferroelectric devices with exotic properties.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Materials Science, Multidisciplinary
Sriram P. Ramkumar, Elizabeth A. Nowadnick
Summary: Layered perovskite oxides are promising platforms for designing novel properties and functionalities, with the ability to tune material properties through controlling octahedral rotation distortions. This study investigates how octahedral rotations respond to pressure in hybrid improper ferroelectrics, revealing the impact of factors such as cation formal charge, tolerance factor, and B-site chemistry on the pressure response. Additionally, the coupling between octahedral rotation and strain order parameters plays a key role in determining the overall pressure response of these materials.
Article
Materials Science, Multidisciplinary
Carmel Dansou, Charles Paillard, Laurent Bellaiche
Summary: The effect of light on the properties of PbTiO3/SrTiO(3 )superlattices was studied using first-principles calculations. Illumination induced a rotation of the polarization and the formation of a space charge region of free carriers, effectively turning the superlattices into p-i-n junctions under light.
Article
Materials Science, Multidisciplinary
Wonshik Kyung, Choong H. Kim, Yeong Kwan Kim, Beomyoung Kim, Chul Kim, Woobin Jung, Junyoung Kwon, Minsoo Kim, Aaron Bostwick, Jonathan D. Denlinger, Yoshiyuki Yoshida, Changyoung Kim
Summary: This study demonstrates that electric field can drive the rotation of octahedra in Sr2RuO4, and the surface electric field originates from the surface electric field, which can be tuned via the screening effect of the overlaid K layer. This work not only establishes that variation in the OR angle can be induced by an electric field, but also provides a way to control OR, which is an important step toward in situ control of the physical properties of perovskite oxides.
NPJ QUANTUM MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
Sagar E. Shirsath, M. Hussein N. Assadi, Ji Zhang, Nitish Kumar, Anil S. Gaikwad, Jack Yang, Helen E. Maynard-Casely, Yee Yan Tay, Jianhao Du, Haoyu Wang, Yin Yao, Zibin Chen, Jinxing Zhang, Shujun Zhang, Sean Li, Danyang Wang
Summary: Perovskite multiferroics have attracted significant attention in the development of multifunctional electronic devices. This study demonstrates the interface-driven multiferroicity in low-cost and eco-friendly bulk polycrystalline materials. The fabricated nanocomposites exhibit both room-temperature ferromagnetism and ferroelectricity, with a robust magnetoelectric coupling.
Article
Materials Science, Multidisciplinary
K. Park, M. O. Yokosuk, M. Goryca, J. J. Yang, S. A. Crooker, S-W Cheong, K. Haule, D. Vanderbilt, H-S Kim, J. L. Musfeldt
Summary: In this study, by combining magneto-optical spectroscopy and first-principles calculations, we reveal the nonreciprocity and formation mechanism of Ni3TeO6 in the toroidal geometry. Additionally, we demonstrate the deterministic control of nonreciprocal directional dichroism in Ni3TeO6. These findings are of great significance for the development of photonics applications that utilize the unique symmetry characteristics of materials.
NPJ QUANTUM MATERIALS
(2022)
Article
Physics, Applied
Yingzhuo Lun, Jiaqian Kang, Wenfu Zhu, Jianming Deng, Xingan Jiang, Cheng Zhu, Qi Ren, Xian Zi, Ziyan Gao, Tianlong Xia, Zishuo Yao, Xueyun Wang, Jiawang Hong
Summary: In this work, a reproducible and stable large-area monodomain is achieved in as-grown bulk ferroelectric single crystal Sn2P2S6 by effectively screening the depolarization field with charge carriers from the photoexcited disproportionation reaction of Sn ions. This offers a potential approach for engineering bulk ferroelectrics with a stable monodomain, which is desirable for high-performance ferroelectric electro-optic devices.
JOURNAL OF ADVANCED DIELECTRICS
(2023)
Article
Materials Science, Ceramics
Hongcai Yu, Qingquan Hou, Gongtian Chen, Chao Ma, Xingan Jiang, Jiawang Hong, Zhiyong Zhou, Ruihong Liang, Xianlin Dong, Hanning Xiao, Bin Yang
Summary: In this study, Ca0.8(Na0.5La0.3Bi0.2)0.2Bi2Nb2O9 ceramics were prepared by Na+, Bi3+, and La3+ ternary doping, which showed higher piezoelectric constant and larger electrical resistivity at high temperatures, along with better thermal stability.
CERAMICS INTERNATIONAL
(2023)
Article
Materials Science, Multidisciplinary
Lixiang Rao, Gang Tang, Jiawang Hong
Summary: This study systematically investigates the mechanical and electronic properties of ScXI (X = S, Se) monolayers and their heterostructures using first-principles calculations. The results verify the experimental speculation that bulk ScSI is exfoliable and ScXI (X = S, Se) monolayers are stable. The ScXI monolayers have a comparable Young's modulus to phosphorene but lower stiffness than graphene, MoS2, and h-BN. The band gap and band edge of ScXI (X = S, Se) monolayers can be effectively regulated by strain, and they can form both type II vertical heterostructure and type I lateral heterostructure. The excellent ductility, strain-tuned electronic properties, and heterostructure design make ScXI (X = S, Se) monolayers promising candidates for flexible electronic devices.
PHYSICAL REVIEW MATERIALS
(2023)
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
Physics, Applied
Jiaqian Kang, Ziyan Gao, Changqing Guo, Wenfu Zhu, Houbing Huang, Jiawang Hong, Sang-Wook Cheong, Xueyun Wang
Summary: Hexagonal manganites display three distinct domain patterns: stripe, loop, and vortex. The formation and evolution of vortex networks is still a mystery due to high ferroelectric phase transition temperature and a lack of reliable visualization methods. In this study, by precisely controlling the annealing temperature at T-c, we observed the coexistence of vortices, loops, and stripes. We proposed a merging process between the V-AV pair and the stripe, resulting in two different forms of vortex networks: normal vortex and zigzag vortex. Additionally, the connection between stripe density and V-AV pair orientation, both influenced by crystal self-straining, was analyzed. Capturing this snapshot and providing the experimental database calls for further analysis to understand the evolution of different domain topologies.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Physical
Qi Ren, Yingzhuo Lun, Yongheng Li, Ziyan Gao, Jianming Deng, Xueyun Wang, Gang Tang, Jiawang Hong
Summary: In this paper, a simple deformability factor consisting of only elastic constants was proposed for high-throughput screening of possible deformable inorganic semiconductors. Through data mining, 99 types of layered materials with high deformability factors were screened out from more than 40,000 materials. The results indicated that the heavy metal halide family generally possesses a high deformability factor. The deformability of the selected material PbI2 was further experimentally verified. This simple factor could be used to rapidly predict the deformability of layered materials and screen candidate inorganic materials for next-generation deformable and flexible electronic devices.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Physical
Zahid Nazir, Yingzhuo Lun, Jialu Li, Gaoling Yang, Mingrui Liu, Shuqi Li, Gang Tang, Guofeng Zhang, Jiawang Hong, Liantuan Xiao, Haizheng Zhong
Summary: Twist provides a new degree of freedom for nanomaterial modifications, which can lead to novel physical properties. By combining experiments and theoretical analyses, the length-dependent relationships between surface energy and twist have been established, with a critical lateral dimension of 30 nm. The geometric asymmetry of twisted nanoplatelets allows for a dissymmetry factor of up to 0.334, and quantum coupling occurs in middle-twisted nanoplatelets. This work deepens our understanding of the twist mechanism of 2D nanoplatelets and opens up possibilities for twistronics and quantum technology applications.
Article
Multidisciplinary Sciences
Xiaolei Wang, Zixuan Shang, Chen Zhang, Jiaqian Kang, Tao Liu, Xueyun Wang, Siliang Chen, Haoliang Liu, Wei Tang, Yu-Jia Zeng, Jianfeng Guo, Zhihai Cheng, Lei Liu, Dong Pan, Shucheng Tong, Bo Wu, Yiyang Xie, Guangcheng Wang, Jinxiang Deng, Tianrui Zhai, Hui-Xiong Deng, Jiawang Hong, Jianhua Zhao
Summary: Manipulating electrical and magnetic anisotropies has been demonstrated in van der Waals multiferroic CuCrP2S6, with axis dependence of current rectifications, magnetic properties and magnon modes. The discovery of spin-flop transition and determination of anisotropy parameters by consistent model fittings and theoretical calculations provide in-depth investigation and quantitative analysis, stimulating potential device applications in artificial bionic synapses, multi-terminal spintronic chips, and magnetoelectric devices.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Yao-Wen Yeh, Sobhit Singh, Guangming Cheng, Nan Yao, Karin M. Rabe, David Vanderbilt, Philip E. Batson, Long Pan, Guofeng Xu, Shiyou Xu
Summary: In this study, the bonding state of calcium carbonate, a crucial building component in organisms, specifically the polymorphs calcite and aragonite, was characterized using valence (low-loss) electron energy loss spectroscopy. The difference in the Ca M23 edge, originating from 3p to 3d states, was found to align with the changes in Ca-O bonds in the two polymorphs. Surprisingly, the measured Ca M23 edge demonstrated qualitative agreement with the calculated partial density of states (PDOS) of Ca-d states, in contrast to the L edges (from 2p to 3d states) heavily influenced by atomic multiplet effect (spin-orbit coupling). These findings indicate that PDOS could potentially be utilized in interpreting the M23 edge of lighter 3d transition metals.
Article
Physics, Applied
Yuanyuan Cui, Shuqi Li, Xiangping Zhang, Tingjun Wang, Xinyu Cao, Shaohua Yan, Xiao Zhang, Hechang Lei, Gang Tang, Jiawang Hong, Xueyun Wang
Summary: The directional dependence of Young's modulus of two-dimensional niobium oxide diiodide (NbOI2) thin flakes was determined using atomic force microscopy-based nanoindentation technique. The Young's moduli along the c-axis and a-axis were found to be 97.27 +/- 62.12 GPa and 51.516 +/- 8.21 GPa, respectively. The anisotropic ratio of up to 1.89 is the highest reported so far in two-dimensional materials.
APPLIED PHYSICS LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Qi Ren, Yongheng Li, Yingzhuo Lun, Gang Tang, Jiawang Hong
Summary: LaWN3 nitride perovskite with polar symmetry has been synthesized and exhibits a large piezoelectric response. However, the thermal transport properties of LaWN3 have not been explored. In this study, the lattice thermal conductivity and phonon properties of LaWN3 are investigated using first-principles calculations. The results show that LaWN3 has comparable thermal conductivity to some typical ferroelectric oxide perovskites and that the coupling effect between phonons and the four-phonon scattering play important roles.
Article
Materials Science, Multidisciplinary
Daniel Seleznev, David Vanderbilt
Summary: The surface-normal component of the surface magnetization is investigated in a three-dimensional antiferromagnetic material. It is found that only crystals exhibiting pseudoscalar symmetry admit well-defined surface magnetizations. Multiple expressions for the quantum local marker are considered, and a particular form of the marker consistently predicts the correct macroscopic hinge currents.
Article
Materials Science, Multidisciplinary
Jinwoong Kim, Cheng-Yi Huang, Hsin Lin, David Vanderbilt, Nicholas Kioussis
Summary: The researchers propose that pristine bulk Bi can serve as a three-dimensional analog of the SSH model, demonstrating the existence of topologically nontrivial and trivial domain walls and providing criteria for determining the Zak phase of domain walls based on parity eigenvalues. They suggest that the dimerization reversal in Bi and the formation of domain walls can be achieved through intense femtosecond laser excitations.
Article
Chemistry, Multidisciplinary
Xingan Jiang, Xiangping Zhang, Xiangyan Han, Jianming Lu, Xueyun Wang, Jiawang Hong
Summary: In this study, the stacking heterostructure of graphene on bulk h-BN was observed using lateral force microscopy. The topographic corrugation of the moire pattern was found to induce considerable curvature and flexoelectric response, with a huge curvature of approximately 10(7) m(-1) and a flexoelectric potential of approximately 10 mV. The domain walls of the moire pattern also exhibited electromechanical and frictional response due to the corrugation-induced flexoelectric response.
