Article
Crystallography
Kejing Zhu, Heng Wang, Yuying Zhu, Yunyi Zang, Yang Feng, Bingbing Tong, Dapeng Zhao, Xiangnan Xie, Kai Chang, Ke He, Chong Liu
Summary: This article describes a study that simplifies and improves the fabrication method of FeSe superconducting films. By using a Se cracking source to enhance the reactivity of the Se flux, it is found that a FeSe film with a stoichiometric ratio close to 1 can be obtained under the appropriate Se/Fe flux ratio. The optimized FeSe film exhibits high-temperature superconductivity without any post-growth treatment.
Article
Physics, Applied
I. Ahmed, S. De Gendt, C. Merckling
Summary: The BaBiO3 perovskite oxide is an interesting material system that exhibits superconductivity when p-doped and predicted topological insulation when n-doped. High-quality single crystalline BaBiO3 films are grown on Si(001) substrates using molecular beam epitaxy, with the growth window established by systematically varying growth parameters.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Xiaotao Xu, Xi He, Anthony T. Bollinger, Xiaoyan Shi, Ivan Bozovic
Summary: A new family of metastable materials, La2-xSrxZnO4 (LSZO), was synthesized by atomic-layer-by-layer molecular beam epitaxy (ALL-MBE), which can form epitaxial materials with a high-temperature superconductor (HTS) compound, La2-xSrxCuO4 (LSCO). By growing La2ZnO4 (LZO) at very low temperatures to form the insulating layer, the superconducting properties of the LSCO electrodes in LSCO/LZO/LSCO trilayers remain undiminished, opening prospects for producing high-quality HTS tunnel junctions.
Article
Chemistry, Multidisciplinary
Tianchao Niu, Miao Zhou
Summary: Boron, the lightest metalloid element, has similar characteristics to carbon in planar and cage molecules. Recent studies have focused on the various structures of mono- and bi-layer boron and their potential applications in materials science. This review highlights the latest achievements in the epitaxial growth of bilayer borophene on noble metal surfaces, discussing the roles of substrate and growth conditions. Bilayer borophene exhibits superior properties compared to single-layer borophene, but its synthesis remains challenging and requires further research.
Article
Chemistry, Multidisciplinary
Kai Chang, John W. D. Villanova, Jing-Rong Ji, Souvik Das, Felix Kuester, Salvador Barraza-Lopez, Paolo Sessi, Stuart S. P. Parkin
Summary: This study reports the formation of atomically sharp lateral heterostructures between a ferroelectric SnTe monolayer and a paraelectric PbTe monolayer. The experiment investigates the bias voltage dependence of the apparent heights of SnTe and PbTe monolayers, revealing unique ferroelectric domain configurations. The mechanism of vortex formation and preferred polarization direction at the horizontal heterointerface is identified through first-principles calculation.
ADVANCED MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
Robert G. Moore, Qiangsheng Lu, Hoyeon Jeon, Xiong Yao, Tyler Smith, Yun-Yi Pai, Michael Chilcote, Hu Miao, Satoshi Okamoto, An-Ping Li, Seongshik Oh, Matthew Brahlek
Summary: The interface between 2D topological Dirac states and an s-wave superconductor has the potential to support Majorana-bound states for quantum computing. The researchers demonstrate that the Fe(Te,Se)/Bi2Te3 system is highly tunable and can be used to realize Majorana-bound states with improved characteristics important for their applications. By reducing doping and improving spin-momentum locking, the desired spin-momentum-locked topological interface states (TIS) can be achieved.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Wenjie Sun, Yueying Li, Ruxin Liu, Jiangfeng Yang, Jiayi Li, Wei Wei, Gangjian Jin, Shengjun Yan, Haoying Sun, Wei Guo, Zhengbin Gu, Zengwei Zhu, Yue Sun, Zhixiang Shi, Yu Deng, Xuefeng Wang, Yuefeng Nie
Summary: Superconductivity has recently been found in infinite-layer nickelates, which provides new opportunities for exploring high-temperature superconductivity mechanisms. However, unlike cuprates, nickelates exhibit a multi-band electronic structure and unexpected isotropic superconductivity, challenging the cuprate-like picture in nickelates.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Runfa Feng, Wei Wang, Changhua Bao, Zichun Zhang, Fei Wang, Hongyun Zhang, Junjie Yao, Yong Xu, Pu Yu, Shuai-Hua Ji, Chen Si, Shuyun Zhou
Summary: This study reports the selective growth of monolayer TaTe2 films with different phases and superstructures by controlling the growth temperature and post-growth annealing treatment. The different electronic structures of 1H-TaTe2 and 1T-TaTe2 films are revealed through experimental measurements and theoretical calculations. The transition from a root 19x root 19 superstructure to a new 2 x 2 superstructure is observed in the annealed 1H-TaTe2 film.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Iolanda Di Bernardo, Joan Ripoll-Sau, Jose Angel Silva-Guillen, Fabian Calleja, Cosme G. Ayani, Rodolfo Miranda, Enric Canadell, Manuela Garnica, Amadeo L. Vazquez L. de Parga
Summary: This study uses scanning tunneling microscopy (STM) to investigate MBE-grown monolayer (ML) TaTe2, and reports the first observation of the coexistence of 1H polymorphic phase and 1T phase, with their relative coverage controlled by adjusting synthesis parameters. Several superperiodic structures compatible with CDWs are observed on the 1T phase. The study provides theoretical insight into the stability of different phases, determined by the balance of Te-Ta and Te-Te interactions.
Article
Chemistry, Multidisciplinary
Qingrui Cao, Evan J. Telford, Avishai Benyamini, Ian Kennedy, Amirali Zangiabadi, Kenji Watanabe, Takashi Taniguchi, Cory R. Dean, Benjamin M. Hunt
Summary: We introduce a novel planar tunneling architecture based on metallic contacts embedded into hBN through-holes, and study the impact of tunnel-contact area and barrier strength on the single-particle density of states of NbSe2 and graphene. We demonstrate a crossover from diffusive to point contacts in NbSe2 devices with 0-layer hBN, and show that reducing the tunnel barrier thickness and area can suppress effects due to phonon-assisted tunneling and defects in the hBN barrier in graphene.
Article
Chemistry, Multidisciplinary
Jin-Hua Nie, Tao Xie, Gang Chen, Wenhao Zhang, Ying-Shuang Fu
Summary: Recent advances in moire' superlattice engineering of two-dimensional heterostructures have enabled the enhancement of multiband superconductivity and effective control of characteristic spectra. This study provides a new approach for engineering proximitized properties of heterostructures through moire' landscape modulation.
Article
Chemistry, Multidisciplinary
Somesh Chandra Ganguli, Viliam Vano, Shawulienu Kezilebieke, Jose L. Lado, Peter Liljeroth
Summary: Transition metal dichalcogenides (TMDC) are a family of two-dimensional materials with diverse quantum states. NbSe2, a d(3) TMDC, is a superconducting material with strong electronic repulsions indicating the presence of competing interactions and correlated insulating states.
Article
Chemistry, Multidisciplinary
Yusong Bai, Tao Jian, Zemin Pan, Jinghao Deng, Xiaoyu Lin, Chao Zhu, Da Huo, Zhengbo Cheng, Yong Liu, Ping Cui, Zhenyu Zhang, Qiang Zou, Chendong Zhang
Summary: We experimentally explore the charge-density wave (CDW) phases in monolayer NbTe2 and discover the presence of 4x4, 4x1, 28x28, and 19x19 phases. These findings are supported by a comprehensive growth phase diagram established through material synthesis and scanning tunneling microscope characterization. Surprisingly, the energetically stable phase is the larger-scale 19x19 phase, contradicting the prior prediction of the 4x4 phase.
Article
Physics, Multidisciplinary
S. Lu, K. Peng, P. D. Wang, A. X. Chen, W. Ren, X. W. Fang, Y. Wu, Z. Y. Li, H. F. Li, F. Y. Cheng, K. L. Xiong, J. Y. Yang, J. Z. Wang, S. A. Ding, Y. P. Jiang, L. Wang, Q. Li, F. S. Li, L. F. Chi
Summary: Monolayer hexagonal MnTe2, synthesized using molecular beam epitaxy under Te rich condition, is found to be a semiconductor with a large bandgap of around 2.78 eV. The valence state of Mn4+ and the atom ratio of ([Te]:[Mn]) confirm the MnTe2 compound.
Review
Physics, Multidisciplinary
Rui-Rui Du
Summary: This article provides a brief introduction to a Majorana platform composed of InAs/GaSb (including InAs/(In)GaSb) semiconductor-superconductor heterostructures. The quantum spin Hall edge state realized in inverted InAs/GaSb is a topologically protected spinless single mode, which can be tuned using front-back dual gates. Similar to other platforms, the proximity effect of a conventional s-wave superconductor on the helical edge is proposed to achieve a Majorana bound state. The article focuses on the materials, devices, and illustrative aspects of this platform.
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(2023)
Review
Materials Science, Biomaterials
Zahid Hussain, Dalya Jamal Ahmed, Ranim Mohammed Alkabra, Hnin Ei Thu, Shahzeb Khan, Mohammad Sohail, Rai Muhammad Sarfraz, Nor Amlizan Ramli
Summary: Wound healing is a complex process that can be promoted by using hyaluronic acid. Hyaluronic acid-based nanomedicines have shown significant efficacy in the treatment of different types of skin injuries.
INTERNATIONAL JOURNAL OF POLYMERIC MATERIALS AND POLYMERIC BIOMATERIALS
(2023)
Article
Polymer Science
Nadiah Zafar, Muhammad Akhlaq, Asif Mahmood, Hira Ijaz, Rai Muhammad Sarfraz, Zahid Hussain, Zainab Masood
Summary: This study reported the use of HPMC/AA hydrogel loaded with AZA for the treatment of Crohn's disease, and demonstrated the potential application of HPMC/AA hydrogel for colon targeting of AZA.
Article
Chemistry, Multidisciplinary
Ro-Ya Liu, Angus Huang, Raman Sankar, Joseph Andrew Hlevyack, Chih-Chuan Su, Shih-Chang Weng, Meng-Kai Lin, Peng Chen, Cheng-Maw Cheng, Jonathan D. Denlinger, Sung-Kwan Mo, Alexei V. Fedorov, Chia-Seng Chang, Horng-Tay Jeng, Tien-Ming Chuang, Tai-Chang Chiang
Summary: This study presents spectroscopic signatures of a predicted topological hourglass semimetal phase in Nb3SiTe6 through angle-resolved photoemission. The results show the existence of linear band crossings and nodal loops, originating from nontrivial Berry phase and predicted glide quantum spin Hall effect. The observation of saddle-like Fermi surface and in situ alkali-metal doping also reveal other band crossings and correlated parabolic bands with accidental nodal loop states.
Article
Chemistry, Analytical
Adrian K. Davey, Zhou Li, Natalie Lefton, Branden E. Leonhardt, Alireza Pourghaderi, Stuart McElhany, Derek Popple, Chunhui Dai, Salman Kahn, Matthew N. Dods, Alex Zettl, Carlo Carraro, Roya Maboudian
Summary: An improved colorimetric CO2 sensor (ED/PSP:ZIF-8) is developed by directly incorporating phenol red into the ZIF-8 metal and linker precursor solutions and blending with ethylenediamine. This sensor exhibits enhanced colorimetric gas response compared to the previous one (PSP-ED/ZIF-8) and has high selectivity to CO2 for indoor air quality monitoring. Furthermore, it can operate effectively across a range of humidity.
SENSORS AND ACTUATORS B-CHEMICAL
(2023)
Article
Chemistry, Multidisciplinary
Qi Liu, Xianyang Lu, Yuxiang Liu, Zhihao Li, Pengfei Yan, Wang Chen, Qinghao Meng, Yongheng Zhang, ChiYung Yam, Liang He, Yu Yan, Yi Zhang, Jing Wu, Thomas Frauenheim, Rong Zhang, Yongbing Xu
Summary: By introducing different contents of Bi adatoms to the surface of monolayer graphene, the carrier concentration and their dynamics have been effectively modulated as probed directly by the time- and angle-resolved photoemission spectroscopy technique. The Bi adatoms are found to assist acoustic phonon scattering events mediated by supercollisions as the disorder effectively relaxes the momentum conservation constraint. A reduced carrier multiplication has been observed, which is related to the shrinking Fermi sea for scattering, as confirmed by time-dependent density functional theory simulation. This work gives insight into hot carrier dynamics in graphene, which is crucial for promoting the application of photoelectric devices.
Article
Materials Science, Multidisciplinary
Derek Popple, Mehmet Dogan, Tony Vo Hoang, Scott Stonemeyer, Peter Ercius, Karen C. Bustillo, Marvin Cohen, Alex Zettl
Summary: Nanotube encapsulation is a powerful technique for achieving unconventional solid configurations. Carbon nanotube encapsulation has been used to create ultranarrow and atomically precise HfTe2 nanoribbons, where a transition from a metallic phase to a semiconducting phase was observed. Computational studies were conducted to investigate the effect of charging on the phase transition and the stability of different atomic configurations.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Yangjin Lee, Young Woo Choi, Kihyun Lee, Chengyu Song, Peter Ercius, Marvin L. Cohen, Kwanpyo Kim, Alex Zettl
Summary: In this study, one-dimensional (1D) chains of GeX2 (X = S or Se) were reported, and the tetrahedral connectivity was modified at the single-chain limit by precise tuning of the edge-and corner-sharing modes between GeX2 blocks, achieved through diameter-dependent 1D confinement inside a carbon nanotube. Atomic-resolution scanning transmission electron microscopy directly confirmed the existence of two distinct types of GeX2 chains. Density functional theory calculations corroborated the diameter-dependent stability of the system and revealed an intriguing electronic structure that sensitively depended on tetrahedral connectivity and composition.
Article
Multidisciplinary Sciences
Wenyu Zhao, Shaoxin Wang, Sudi Chen, Zuocheng Zhang, Kenji Watanabe, Takashi Taniguchi, Alex Zettl, Feng Wang
Summary: Thermally excited electrons and holes form a quantum-critical Dirac fluid in ultraclean graphene. The electrodynamic responses of this fluid are described by a universal hydrodynamic theory. Researchers observed the presence of a hydrodynamic plasmon and energy wave in ultraclean graphene using on-chip terahertz spectroscopy technique. These findings open up new opportunities to explore collective hydrodynamic excitations in graphene systems.
Article
Physics, Multidisciplinary
Wu Shi, Salman Kahn, Nicolas Leconte, Takashi Taniguchi, Kenji Watanabe, Michael Crommie, Jeil Jung, Alex Zettl
Summary: Recent studies have explored intriguing quantum phenomena in vdW heterostructures and superlattices but mainly focused on the moderate carrier density regime. In this study, we used a newly developed electron beam doping technique to probe high-temperature fractal BZ quantum oscillations in the extreme doping regimes. By accessing ultrahigh electron and hole densities beyond the dielectric breakdown limit, we observed nonmonotonic carrier-density dependence of fractal BZ states and up to fourth-order fractal BZ features. Theoretical simulations explained these findings as a weakening of superlattice effects at high carrier densities.
PHYSICAL REVIEW LETTERS
(2023)
Article
Multidisciplinary Sciences
Yekai Song, Chunjing Jia, Hongyu Xiong, Binbin Wang, Zhicheng Jiang, Kui Huang, Jinwoong Hwang, Zhuojun Li, Choongyu Hwang, Zhongkai Liu, Dawei Shen, Jonathan A. Sobota, Patrick Kirchmann, Jiamin Xue, Thomas P. Devereaux, Sung-Kwan Mo, Zhi-Xun Shen, Shujie Tang
Summary: The authors report electronic properties of monolayer ZrTe2 from ARPES and STM measurements that are consistent with the preformed exciton gas phase, a precursor for the excitonic insulator.
NATURE COMMUNICATIONS
(2023)
Article
Multidisciplinary Sciences
Junyu Zong, Zhao-Yang Dong, Junwei Huang, Kaili Wang, Qi-Wei Wang, Qinghao Meng, Qichao Tian, Xiaodong Qiu, Yuyang Mu, Li Wang, Wei Ren, Xuedong Xie, Wang Chen, Yongheng Zhang, Can Wang, Fang-Sen Li, Shao-Chun Li, Jian-Xin Li, Hongtao Yuan, Yi Zhang
Summary: In this study, the van Hove singularity (VHS) in the epitaxial monolayer (ML) 1T-VSe2 film was successfully manipulated by the giant magnified dielectric constant er of SrTiO3(111) substrate with cooling, leading to a two-dimensional (2D) itinerant ferromagnetic state below 3.3 K. The manipulation of VHS was ascribed to the physical origin of the itinerant ferromagnetic state in ML 1T-VSe2, as supported by angle-resolved photoemission spectroscopy (ARPES) and theoretical analysis. These findings demonstrate the potential of controlling the ferromagnetic state in 2D systems through VHS engineering, expanding the application possibilities of 2D magnets for next-generation information technology.
Article
Nanoscience & Nanotechnology
Wen Wan, Rishav Harsh, Paul Dreher, Fernando de Juan, Miguel M. Ugeda
Summary: Chemical substitution is a promising approach to explore collective phenomena in low-dimensional quantum materials. Transition metal dichalcogenide alloys are shown to be ideal platforms for this purpose. We demonstrate the emergence of superconductivity in single-layer TaSe2 through minute electron doping using substitutional W atoms. The temperature and magnetic field dependence of the superconducting state of Ta1-delta W delta Se2 are investigated using scanning tunneling spectroscopy. A superconducting dome spanning 0.003 < delta < 0.03 with a maximized critical temperature of 0.9 K is observed, which is significantly higher than that of bulk TaSe2 (T-C = 0.14 K). The superconductivity is attributed to an increase in density of states as the Fermi surface approaches a van Hove singularity, but gradually weakens as the singularity is reached, shaping the superconducting dome. Doping-dependent measurements suggest the development of a Coulomb glass phase triggered by disorder due to W dopants.
NPJ 2D MATERIALS AND APPLICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Chunhui Dai, Derek Popple, Cong Su, Ji-Hoon Park, Kenji Watanabe, Takashi Taniguchi, Jing Kong, Alex Zettl
Summary: The engineering of atomically-precise nanopores in two-dimensional materials holds exciting opportunities for fundamental science studies and various applications. The exceptional stability of hexagonal boron nitride (h-BN) suggests that exposed h-BN nanopores can retain their atomic structure even in gas or liquid environments over time. However, this study discovers that h-BN nanopores undergo dramatic changes in geometry due to atom motion and edge contamination adsorption, even at room temperature.
COMMUNICATIONS CHEMISTRY
(2023)
Article
Nanoscience & Nanotechnology
Ji-Eun Lee, Kyoo Kim, Van Quang Nguyen, Jinwoong Hwang, Jonathan D. Denlinger, Byung Il Min, Sunglae Cho, Hyejin Ryu, Choongyu Hwang, Sung-Kwan Mo
Summary: The thermoelectric performance of SnSe is strongly influenced by the low-energy electron band structure, which provides a high density of states in a narrow energy range due to the multi-valley valence band maximum (VBM). The binding energy of the VBM in SnSe is found to be tuned by the population of Sn vacancies, which is determined by the cooling rate during sample growth, as revealed by angle-resolved photoemission spectroscopy measurements and first-principles calculations. The shift in VBM closely correlates with the thermoelectric power factor, while the effective mass remains largely unchanged with variations in Sn vacancy population. These findings demonstrate that the low-energy electron band structure plays a crucial role in the high thermoelectric performance of hole-doped SnSe, offering a promising route to engineering intrinsic defect-induced thermoelectric performance through sample growth conditions without requiring additional ex-situ processes.
Article
Astronomy & Astrophysics
XiaoDong Qiu, KaiLi Wang, Peng Chen, Yi Zhang
Summary: The electronic structure of a material plays a crucial role in determining its properties, and angle-resolved photoemission spectroscopy (ARPES) is an advanced technique used to directly observe the electronic structure. This review article provides an overview of the ARPES system and discusses the recent progress in studying the electronic structures and physical properties of 2D materials. The reviewed 2D materials include graphene, h-BN, single element 2D materials, and transition metal dichalcogenides (TMDCs).
SCIENTIA SINICA-PHYSICA MECHANICA & ASTRONOMICA
(2023)
