Article
Physics, Multidisciplinary
J. S. Zhou, R. Z. Xu, X. Q. Yu, F. J. Cheng, W. X. Zhao, X. Du, S. Z. Wang, Q. Q. Zhang, X. Gu, S. M. He, Y. D. Li, M. Q. Ren, X. C. Ma, Q. K. Xue, Y. L. Chen, C. L. Song, L. X. Yang
Summary: In this study, the electronic structures of superconducting K3C60 thin films were systematically investigated using high-resolution angle-resolved photoemission spectroscopy. A dispersive energy band crossing the Fermi level, Jahn-Teller active phonon modes, and strong electron-phonon coupling were observed. The electron-phonon coupling constant was estimated to be approximately 1.2, and an isotropic nodeless superconducting gap was observed. These results provide important insights into the mechanism of unusual superconductivity in fulleride compounds.
PHYSICAL REVIEW LETTERS
(2023)
Article
Nanoscience & Nanotechnology
Gloria Anemone, Pablo Casado Aguilar, Manuela Garnica, Fabian Calleja, Amjad Al Taleb, Chia-Nung Kuo, Chin Shan Lue, Antonio Politano, Amadeo L. Vazquez de Parga, Giorgio Benedek, Daniel Farias, Rodolfo Miranda
Summary: The electron-phonon interaction in type II Dirac semimetallic 1T-PdTe2 has been determined using helium atom scattering, indicating a substantial electron-phonon coupling which is crucial for its superconductivity. This coupling value, along with the surface Debye temperature, accurately predicts the superconducting critical temperature, suggesting that the topological states of a Dirac cone have minimal influence on the onset of superconductivity.
NPJ 2D MATERIALS AND APPLICATIONS
(2021)
Article
Chemistry, Multidisciplinary
Jung Hyun Ryu, Jeong-Gyu Kim, Bongjae Kim, Kyoo Kim, Sooran Kim, Jae-Hoon Park, Byeong-Gyu Park, Younghak Kim, Kyung-Tae Ko, Kimoon Lee
Summary: Researchers have discovered experimental evidence of strong interlayer coupling in 2D PdSe2, which originates from the unique directional bonding of Pd d orbitals. This interlayer coupling plays a decisive role in the strong layer-dependency of the band gap.
Article
Physics, Multidisciplinary
Shuaishuai Li, Taimin Miao, Chaohui Yin, Yinghao Li, Hongtao Yan, Yiwen Chen, Bo Liang, Hao Chen, Wenpei Zhu, Shenjin Zhang, Zhimin Wang, Fengfeng Zhang, Feng Yang, Qinjun Peng, Chengtian Lin, Hanqing Mao, Guodong Liu, Zuyan Xu, Lin Zhao, X. J. Zhou
Summary: In this study, spatially-resolved laser-based high-resolution angle resolved photoemission spectroscopy (ARPES) measurements were performed on the optimally-doped YBa2Cu3O7-delta (Y123) superconductor. For the first time, clear bulk electronic properties were observed in the region from the cleaved surface. The Fermi surface and band structures of Y123 were determined, and a nodeless superconducting gap consistent with the d+is gap form was identified.
Article
Chemistry, Multidisciplinary
Zhenwei Ou, Bin Peng, Weibin Chu, Zhe Li, Cheng Wang, Yan Zeng, Hongyi Chen, Qiuyu Wang, Guohua Dong, Yongyi Wu, Ruibin Qiu, Li Ma, Lili Zhang, Xiaoze Liu, Tao Li, Ting Yu, Zhongqiang Hu, Ti Wang, Ming Liu, Hongxing Xu
Summary: In this study, the carrier transport behavior mediated by the electron-phonon coupling in BiFeO3 epitaxial thin films is directly observed. Acoustic phonons generated by the inverse piezoelectric effect are coupled with photocarriers, leading to the observation of a doughnut shape carrier distribution. The results provide an effective approach to investigate the effects of electron-phonon interactions and are of great importance for designing and improving electronic devices.
Article
Chemistry, Physical
Jiwon Jeon, Youngjae Kim, J. D. Lee
Summary: Pseudospin, a fundamental quantum number in graphene, can be changed by the rotation of phonons. By observing the phonon satellite accompanying the linearly pumped electron to the upper Dirac cone, we found that pseudospin exhibits rotation, nonzero angular momentum, and Berry curvature. We also identified the phonon responsible for pseudospin rotation as an elliptically polarized phonon, which can induce chiral phonon excitation without circularly polarized pumping.
Article
Physics, Applied
Hayder A. Al-Atabi, Xiaotian Zhang, Shanmei He, Cheng Chen, Yulin Chen, Eli Rotenberg, James H. Edgar
Summary: This study aims to investigate the stoichiometry and electronic structure of scandium nitride (ScN) by growing ScN (100) single crystals under specific conditions and obtaining core level spectra data using X-ray photoelectron spectroscopy.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
V. R. Sodisetti, S. Ncube, C. Coleman, R. M. Erasmus, E. Flahaut, S. Bhattacharyya
Summary: The study of spin-phonon coupling in Gd-filled double-walled carbon nanotubes revealed phonon frequency hardening at low temperatures, attributed to phonon renormalization induced by spin-phonon coupling interaction. The estimated spin-phonon coupling constants for the G(ext)(+) and G(int)(+) phonon modes were found to be 12.2 and 5.0 cm(-1) respectively, suggesting potential benefits for designing effective molecular qubits in a one-dimensional system with a three times higher spin-phonon coupling than other multiferroic compounds.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Multidisciplinary Sciences
Jiaji Ma, Ruihan Yang, Hanghui Chen
Summary: By using first-principles methods, the study reveals a strong coupling between itinerant electrons and soft polar phonons in doped strong ferroelectrics, deviating from the weakly coupled electron mechanism proposed by Anderson/Blount. The total electron-phonon coupling in doped BaTiO3 increases to about 0.6 around the critical concentration, enabling the induction of phonon-mediated superconductivity. Introducing epitaxial strain to lower the crystal symmetry of doped BaTiO3 further boosts the superconducting temperature through a substantial coupling between itinerant electrons and acoustic phonons.
NATURE COMMUNICATIONS
(2021)
Review
Chemistry, Multidisciplinary
Yiwei Li, Qiang Wan, Nan Xu
Summary: The past decade has seen significant progress in 2D materials, particularly in the field of artificial moire superlattices. These superlattices exhibit a range of quantum phenomena beyond their constituent materials, thanks to their nontrivial electronic structures. Modern ARPES techniques allow for direct visualization of these electronic structures, providing valuable insights into the fundamental physics of moire superlattice systems and guiding the design of novel devices.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Antonio Rossi, Cameron Johnson, Jesse Balgley, John C. Thomas, Luca Francaviglia, Riccardo Dettori, Andreas K. Schmid, Kenji Watanabe, Takashi Taniguchi, Matthew Cothrine, David G. Mandrus, Chris Jozwiak, Aaron Bostwick, Erik A. Henriksen, Alexander Weber-Bargioni, Eli Rotenberg
Summary: We investigated the electronic properties of a graphene and a-ruthenium trichloride (a-RuCl3) heterostructure and observed massive charge transfer from graphene to a-RuCl3. This strong coupling between the two materials can lead to novel electronic phenomena. Understanding these properties is crucial for designing next generation low-power optoelectronic devices.
Article
Chemistry, Multidisciplinary
Gary Wan, Alex Croot, Neil A. Fox, Mattia Cattelan
Summary: This paper presents an alternative method based on thermalized photoelectrons for investigating the unoccupied electronic states emitted from crystal surfaces. The approach is demonstrated on diamond and copper, revealing the unoccupied state band structure and allowing for experimental determination of the transverse effective mass. This method offers a convenient path for interpreting angle-resolved photoemission data and extracting information about empty states.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Article
Physics, Multidisciplinary
Zhengwang Cheng, Zhilong Hu, Shaojian Li, Xinguo Ma, Zhifeng Liu, Mei Wang, Jing He, Wei Zou, Fangsen Li, Zhiqiang Mao, Minghu Pan
Summary: The study investigates the band structure of the "square-net" topological material ZrGeS, revealing its unique electronic properties suitable for exploring Dirac-fermions related physics and applications of topological devising.
NEW JOURNAL OF PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Shu-Yu Liu, Shuang-Xing Zhu, Qi-Yi Wu, Chen Zhang, Peng-Bo Song, You-Guo Shi, Hao Liu, Zi-Teng Liu, Jiao-Jiao Song, Fan-Ying Wu, Yin-Zou Zhao, Xiao-Fang Tang, Ya-Hua Yuan, Han Huang, Jun He, H. Y. Liu, Yu-Xia Duan, Jian-Qiao Meng
Summary: The study investigated the ultrafast carrier and phonon dynamics of Dirac semi-metal PdTe2 single-crystal using ultrafast optical pump-probe spectroscopy. It revealed fast relaxation process from electron-phonon thermalization and slower relaxation process from phonon-assisted electron-hole recombination. The analysis suggested the A(1g) mode contributes greatly to superconductivity and high-frequency phonons are involved in forming Cooper pairs in PdTe2.
RESULTS IN PHYSICS
(2021)
Article
Physics, Multidisciplinary
Zi-Teng Liu, Chen Zhang, Qi-Yi Wu, Hao Liu, Bo Chen, Zhi-Bo Yin, Sheng-Tao Cui, Zhe Sun, Shuang-Xing Zhu, Jiao-Jiao Song, Yin-Zou Zhao, Hong-Yi Zhang, Xue-Qing Ye, Fan-Ying Wu, Shu-Yu Liu, Xiao-Fang Tang, Ya-Hua Yuan, Yun-Peng Wang, Jun He, Hai-Yun Liu, Yu-Xia Duan, Jian-Qiao Meng
Summary: The recently discovered ternary chalcogenide superconductor Bi2Rh3Se2 has gained attention for studying the interplay between charge density wave (CDW) order and superconductivity. The nature of its phase transition around 240 K, whether it is due to the formation of CDW, has been controversial. In this study, the electronic structure of Bi2Rh3Se2 was investigated using angle-resolved photoemission spectroscopy, and it was found that the phase transition at 240 K is a second-order CDW transition. The results provide insights into the CDW order and superconductivity in Bi2Rh3Se2.
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(2023)
Article
Physics, Multidisciplinary
Rui Lou, Alexander Fedorov, Qiangwei Yin, Andrii Kuibarov, Zhijun Tu, Chunsheng Gong, Eike F. Schwier, Bernd Buechner, Hechang Lei, Sergey Borisenko
Summary: The entanglement of charge density wave (CDW), superconductivity, and topologically nontrivial electronic structure has been discovered in the kagome metal AV3Sb5 (A = K, Rb, Cs) family recently. Using high-resolution angle-resolved photoemission spectroscopy, the electronic properties of CDW and superconductivity in CsV3Sb5 are studied. The spectra around K over line exhibit a peak-dip-hump structure associated with two separate branches of dispersion, indicating the isotropic CDW gap opening below EF. The presence of a superconducting gap on both the electron band around Gamma over line and the flat band around K suggests multiband superconductivity. Our results shed light on the controversial origin of the CDW and provide insights into the relationship between CDW and superconductivity.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Physical
Lorenzo Francesco Madeo, Patrizia Sarogni, Giuseppe Cirillo, Orazio Vittorio, Valerio Voliani, Manuela Curcio, Tyler Shai-Hee, Bernd Buechner, Michael Mertig, Silke Hampel
Summary: A hybrid hydrogel was developed by loading curcumin onto graphene oxide nanosheets and blending them into an alginate hydrogel. The resulting system showed improved stability and exhibited strong anticancer effects.
Article
Materials Science, Multidisciplinary
T. Klaproth, E. Mueller, C. Habenicht, B. Buechner, M. Knupfer, M. Roslova, A. Isaeva, T. Doert, A. Koitzsch
Summary: Transition metal trichlorides exhibit peculiar and versatile magnetic properties. This study reveals that transition metal substitution can modify the optical properties of the host without compromising its electronic structure. The findings highlight the potential of material engineering in trichlorides.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Chemistry, Physical
Felix Talnack, Sebastian Hutsch, Michael Bretschneider, Yulia Krupskaya, Bernd Buechner, Marc Malfois, Mike Hambsch, Frank Ortmann, Stefan C. B. Mannsfeld
Summary: Polymorphism refers to the ability of many organic molecules to adopt different crystal structures without changing their chemical structure. It has been found to have an impact on the solid-state properties of organic materials, such as charge transport in organic semiconductors. In this study, a new polymorphic crystal structure of the p-type small molecule semiconductor C10-DNTT is presented. The transition between different crystal structures was observed during heating, and the thin-film crystal structure of both polymorphs was refined using optical microscopy and X-ray scattering measurements. The thermal expansion and anisotropic molecular interactions were further analyzed using density-functional theory calculations.
MOLECULAR SYSTEMS DESIGN & ENGINEERING
(2022)
Article
Chemistry, Multidisciplinary
Felix Hansen, Rico Fucke, Titouan Charvin, Samuel Froeschke, Daniel Wolf, Romain Giraud, Joseph Dufouleur, Nico Graessler, Bernd Buechner, Peer Schmidt, Silke Hampel
Summary: This study proposes a method for the synthesis of mixed crystals of bismuth and antimony tellurides, which belong to the V2VI3 material family. The ideal synthesis conditions were determined through thermodynamic calculations and optimization experiments. The synthesized nanosheets exhibit high crystallinity and quality, with a significantly reduced carrier density compared to the binary compounds.
CRYSTAL GROWTH & DESIGN
(2022)
Article
Chemistry, Multidisciplinary
Bertold Rasche, Julius Brunner, Tim Schramm, Madhav Prasad Ghimire, Ulrike Nitzsche, Bernd Buchner, Romain Giraud, Manuel Richter, Joseph Dufouleur
Summary: This paper presents a method using atomic force microscopy to measure the cleavage energy of van der Waals materials and quasi-two-dimensional materials. The method is validated through experiments and can be used as a tool for manipulating exfoliated flakes, offering a new route for the fabrication of nanostructures.
Article
Multidisciplinary Sciences
Sergey Borisenko, Alexander Fedorov, Andrii Kuibarov, Marco Bianchi, Volodymyr Bezguba, Paulina Majchrzak, Philip Hofmann, Peter Baumgaertel, Vladimir Voroshnin, Yevhen Kushnirenko, Jaime Sanchez-Barriga, Andrei Varykhalov, Ruslan Ovsyannikov, Igor Morozov, Saicharan Aswartham, Oleh Feia, Luminita Harnagea, Sabine Wurmehl, Alexander Kordyuk, Alexander Yaresko, Helmuth Berger, Bernd Buechner
Summary: Fermi surfaces are crucial for understanding the properties of crystalline metals and semiconductors. A new angle-resolved photoemission spectroscopy technique is presented that allows for fast and high-resolution mapping of the Fermi surface.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Multidisciplinary
Edgar Abarca Morales, Gesa-R. Siemann, Andela Zivanovic, Philip A. E. Murgatroyd, Igor Markovic, Brendan Edwards, Chris A. Hooley, Dmitry A. Sokolov, Naoki Kikugawa, Cephise Cacho, Matthew D. Watson, Timur K. Kim, Clifford W. Hicks, Andrew P. Mackenzie, Phil D. C. King
Summary: We present the evolution of the electronic structure at the surface of Sr2RuO4 under large in-plane uniaxial compression, resulting in anisotropic B1g strains. Using angle-resolved photoemission, we observe a sequence of Lifshitz transitions that reshape the electronic structure and van Hove singularities on the surface. Our study reveals the nature of structural distortions at oxide surfaces and the possibility of controlling the density of state singularities for the realization of collective states at the Sr2RuO4 surface.
PHYSICAL REVIEW LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Abdul-Vakhab Tcakaev, Bastian Rubrecht, Jorge. Facio, Volodymyr. B. Zabolotnyy, Laura. T. Corredor, Laura. C. Folkers, Ekaterina Kochetkova, Thiago R. F. Peixoto, Philipp Kagerer, Simon Heinze, Hendrik Bentmann, Robert. J. Green, Pierluigi Gargiani, Manuel Valvidares, Eugen Weschke, Maurits. W. Haverkort, Friedrich Reinert, Jeroen van den Brink, Bernd Buechner, Anja U. B. Wolter, Anna Isaeva, Vladimir Hinkov
Summary: The recent discovery of the quantum anomalous Hall effect (QAHE) in MnBi2Te4 and MnBi4Te7 indicates the potential of the (MnBi2Te4)(Bi2Te3)(n) family for further improvements in QAHE. The ferromagnetic (FM) ordered MnBi2Te4 septuple layers (SLs) in this family contribute to its promising nature. However, achieving QAHE in MnBi2Te4 and MnBi4Te7 is complicated due to the substantial antiferromagnetic (AFM) coupling between the SLs. By interlacing the SLs with an increasing number of Bi2Te3 quintuple layers (QLs), an FM state advantageous for QAHE can be stabilized. The mechanisms driving the FM state and the number of necessary QLs are not yet understood, and the surface magnetism remains unclear. This study demonstrates robust FM properties in MnBi6Te10 (n = 2) and establishes that its origin lies in the Mn/Bi intermixing phenomenon, thus consolidating its potential for QAHE at elevated temperatures.
Article
Materials Science, Multidisciplinary
A. Garrison Linn, Peipei Hao, Kyle N. Gordon, Dushyant Narayan, Bryan S. Berggren, Nathaniel Speiser, Sonka Reimers, Richard P. Campion, Vit Novak, Sarnjeet S. Dhesi, Timur K. Kim, Cephise Cacho, Libor Smejkal, Tomas Jungwirth, Jonathan D. Denlinger, Peter Wadley, Daniel S. Dessau
Summary: This study reports direct measurements of the electronic structure of tetragonal CuMnAs thin films using ARPES, including Fermi surfaces and energy-wavevector dispersions. After correcting for a chemical potential shift, there is excellent agreement between the experimental results and theoretical calculations. 2x1 surface reconstructions are also observed in low energy electron diffraction and ARPES. This work emphasizes the importance of controlling the chemical potential in tetragonal CuMnAs to explore and exploit tunable Dirac fermions.
NPJ QUANTUM MATERIALS
(2023)
Article
Multidisciplinary Sciences
Kifu Kurokawa, Shunsuke Isono, Yoshimitsu Kohama, So Kunisada, Shiro Sakai, Ryotaro Sekine, Makoto Okubo, Matthew. D. D. Watson, Timur. K. K. Kim, Cephise Cacho, Shik Shin, Takami Tohyama, Kazuyasu Tokiwa, Takeshi Kondo
Summary: By studying the inner CuO2 planes of a six-layered compound, the authors find that even the slightest amount of carriers can turn a Mott insulating state into a metallic state with long-lived quasiparticles. Furthermore, they observe a phase transition from the superconducting to the metallic states at 4% doping.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
R. Z. Xu, X. Du, J. S. Zhou, X. Gu, Q. Q. Zhang, Y. D. Li, W. X. Zhao, F. W. Zheng, M. Arita, K. Shimada, T. K. Kim, C. Cacho, Y. F. Guo, Z. K. Liu, Y. L. Chen, L. X. Yang
Summary: Using high-resolution angle-resolved photoemission spectroscopy and ab initio calculation, we systematically investigate the electronic structure of TaTe4 and observe a CDW gap as large as 290 meV at 26 K, which persists up to 500 K. The CDW-modulated band structure shows a complex reconstruction that closely correlates with the lattice distortion. Our ab initio calculation reveals that the large CDW gap mainly opens in the electronic states with out-of-plane orbital components, while in-gap metallic states originate from in-plane orbitals, suggesting an orbital texture that couples with the CDW order.
NPJ QUANTUM MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Q. Q. Zhang, Y. Shi, K. Y. Zhai, W. X. Zhao, X. Du, J. S. Zhou, X. Gu, R. Z. Xu, Y. D. Li, Y. F. Guo, Z. K. Liu, C. Chen, S. K. Mo, T. K. Kim, C. Cacho, J. W. Yu, W. Li, Y. L. Chen, Jiun-Haw Chu, L. X. Yang
Summary: In this paper, the electronic structure and transport properties of EuTe4 were investigated using high-resolution angle-resolved photoemission spectroscopy (ARPES), magnetoresistance (MR) measurements, and scanning tunneling microscopy (STM). A CDW gap of approximately 200 meV was observed at low temperatures, which persists up to 400 K, suggesting a higher transition temperature. The negatively large MR at low temperatures may be related to the canting of magnetically ordered Eu spins.
Article
Physics, Multidisciplinary
P. Kagerer, C. I. Fornari, S. Buchberger, T. Tschirner, L. Veyrat, M. Kamp, A. V. Tcakaev, V. Zabolotnyy, S. L. Morelhao, B. Geldiyev, S. Mueller, A. Fedorov, E. Rienks, P. Gargiani, M. Valvidares, L. C. Folkers, A. Isaeva, B. Buechner, V. Hinkov, R. Claessen, H. Bentmann, F. Reinert
Summary: Inducing a magnetically-induced gap in the Dirac point of a three-dimensional topological insulator can result in dissipationless charge and spin currents. In this study, the authors use a ferromagnetic extension technique to create a robust 2D ferromagnetic material on the surface of a 3D topological insulator. The results demonstrate the opening of a sizable magnetic gap in the 2D ferromagnetic phase, while the surface remains gapless in the paramagnetic phase.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
A. Kuibarov, A. Fedorov, V. Bezguba, H. Berger, A. Yaresko, V. Voroshnin, A. Kordyuk, P. Baumgaertel, B. Buechner, S. Borisenko
Summary: Using angle-resolved photoemission spectroscopy, this study revisits the electronic structure of BiTeI and proposes an alternative description based on the experimentally determined crystal structure. The results show that BiTeI is a topological 3D Dirac semimetal with only two, well isolated Dirac points in its band structure.
