Article
Physics, Multidisciplinary
Shaofeng Duan, Wei Xia, Chaozhi Huang, Shichong Wang, Lingxiao Gu, Haoran Liu, Dao Xiang, Dong Qian, Yanfeng Guo, Wentao Zhang
Summary: The ultrafast electronic structures of 1T-TiSe2, a charge density wave material, were studied using high-resolution time- and angle-resolved photoemission spectroscopy. The study found that the populations of quasiparticles drove ultrafast electronic phase transitions in 1T-TiSe2 within 100 fs after photoexcitation. A metastable metallic state, different from the equilibrium normal phase, was observed below the charge density wave transition temperature. The photoinduced metastable metallic state resulted from the coherent electron-phonon coupling process, where the motion of atoms was halted, and its lifetime was prolonged with increasing pump fluence.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Zijian Lin, Cuixiang Wang, A. Balassis, J. P. Echeverry, A. S. Vasenko, V. M. Silkin, E. V. Chulkov, Youguo Shi, Jiandi Zhang, Jiandong Guo, Xuetao Zhu
Summary: Through a systematic study of the plasmon behavior of 1T-TiSe2, differences between plasmons and phonon modes are revealed, and a significant relationship between band gap evolution and plasmon lifetime is discovered.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Physical
Mukhtar Lawan Adam, Hongen Zhu, Zhanfeng Liu, Shengtao Cui, Pengjun Zhang, Yi Liu, Guobin Zhang, Xiaojun Wu, Zhe Sun, Li Song
Summary: By intercalating Sn atoms, the CDW phase in 1T-TiSe2 single crystals can be gradually suppressed, inducing charge doping and modulating the intrinsic electronic properties. Temperature-dependent ARPES results reveal the role of exciton-phonon interaction and the Jahn-Teller mechanism in the formation of CDW in this material.
Article
Materials Science, Multidisciplinary
Christoph Emeis, Sanjoy Kr Mahatha, Sebastian Rohlf, Kai Rossnagel, Fabio Caruso
Summary: This study combines ab initio calculations and ARPES to investigate the electron-plasmon interaction in highly doped semiconducting 1T-HfS2. Experimental results reveal the emergence of satellite spectral features near quasiparticle excitations, indicating coupling to bosonic excitations. First-principles calculations demonstrate that these features can be attributed to electronic coupling to carrier plasmons. Additionally, reduced screening at the surface enhances the electron-plasmon interaction and leads to the formation of plasmonic polarons.
Article
Electrochemistry
J. E. Antonio, J. M. Cervantes, J. L. Rosas-Huerta, J. Pilo, E. Carvajal, R. Escamilla
Summary: This study investigated the electronic and mechanical properties of bulk TiSe2, as well as the effects of confinement into mono-, bi-, and tri-layered systems. The calculations showed that the mono-, bi-, and tri-layered systems exhibit metallic behavior similar to the bulk material. Additionally, the addition of Li atoms in monolayers may be favorable for electronic transport.
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
(2021)
Article
Materials Science, Multidisciplinary
Natalia V. Morozova, Aleksandr Yu. Usik, Igor V. Korobeinikov, Alexander N. Titov, Sergey V. Ovsyannikov
Summary: A semiconductor-metal transition was observed in Cu-intercalated TiSe2 single crystals (x <= 0.1) at room temperature under mechanical stress. The crystals can be transformed from semiconductors to metals by applying a stress of 1-3 GPa. This suggests the potential application of CuxTiSe2 crystals in optoelectronic micro-devices where their characteristics can be controlled by stress or strain.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
Article
Chemistry, Physical
Kai Hu, Li-Min Guan, Dong Han, Fuyang Liu, Sheng-Yi Xie
Summary: By investigating the phase transformations of layered transition-metal dichalcogenides under high pressure, using TiSe2 as a case study, it was found that the evolution of vacancies plays a crucial role. The proposed densification model reveals how the symmetry-breaking phase of spatial chemical bonding restores symmetry under isotropic external pressure.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Physics, Multidisciplinary
Max Burian, Michael Porer, Jose R. L. Mardegan, Vincent Esposito, Sergii Parchenko, Bulat Burganov, Namrata Gurung, Mahesh Ramakrishnan, Valerio Scagnoli, Hiroki Ueda, Sonia Francoual, Federica Fabrizi, Yoshikazu Tanaka, Tadashi Togashi, Yuya Kubota, Makina Yabashi, Kai Rossnagel, Steven L. Johnson, Urs Staub
Summary: In 1T-TiSe2, under optical excitation, the periodic lattice deformation is strongly suppressed while the charge density wave related Se 4p orbital order remains mostly intact. The melting of both structural and electronic order occurs four to five times faster than expected, suggesting a structurally assisted weakening of excitonic correlations.
PHYSICAL REVIEW RESEARCH
(2021)
Article
Chemistry, Physical
Yonghao Wang, Zesen Lei, Meng Guo, Qilong Sun, Cui Jin, Ruishan Tan, Ying Dai
Summary: This study systematically investigates the electronic and magnetic properties of 1T-MX2 monolayers and discovers the significant influence of biaxial strain and carrier doping on their ferromagnetic behavior. In addition to stable ferromagnetic states, three of the monolayers exhibit tunable magnetocrystalline anisotropy depending on the applied strain and carrier doping. The changes in magnetocrystalline anisotropy are mainly attributed to alterations in specific M-derived 3d states induced by strain or carrier doping, which affect their spin-orbit coupling energies.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
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
Multidisciplinary Sciences
Cheng Hu, Jianfa Zhao, Qiang Gao, Hongtao Yan, Hongtao Rong, Jianwei Huang, Jing Liu, Yongqing Cai, Cong Li, Hao Chen, Lin Zhao, Guodong Liu, Changqing Jin, Zuyan Xu, Tao Xiang, X. J. Zhou
Summary: Researchers visualize the electronic structure evolution of a Mott insulator within the full Mott gap region and address fundamental issues, providing key information on the electronic evolution when doping a Mott insulator and establishing a basis for developing microscopic theories for cuprate superconductivity.
NATURE COMMUNICATIONS
(2021)
Article
Materials Science, Multidisciplinary
Marcel Holtmann, Peter Krueger, Koji Miyamoto, Taichi Okuda, Kenya Shimada, Markus Donath
Summary: The surface electronic structure of Re(0001) was investigated using experimental and theoretical methods. Spin-and angle-resolved photoemission were employed to study the spin-dependent energy dispersion of electronic states. Band-structure calculations based on density-functional theory were compared with the experimental results. Additional calculations were performed to consider transitions into final states. It was found that Rashba-type spin splittings were observed and there was no out-of-plane spin polarization due to the monatomic steps on the real Re(0001) surface.
Article
Physics, Multidisciplinary
Wei Zhi-Yuan, Hu Yong, Zeng Ling-Yong, Li Ze-Yu, Qiao Zhen-Hua, Luo Hui-Xia, He Jun-Feng
Summary: Transition metal dichalcogenides (TMDs) have attracted a lot of interest in condensed matter physics research due to the existence of multiple novel physical phenomena. In this study, the electronic structure of 1T-NbSeTe is examined, and a van Hove singularity (VHS) is identified. The possible role of the VHS and electron-boson coupling in charge density wave and superconductivity is discussed.
ACTA PHYSICA SINICA
(2022)
Article
Chemistry, Multidisciplinary
Woojoo Lee, Yuanxi Wang, Wei Qin, Hyunsue Kim, Mengke Liu, T. Nathan Nunley, Bin Fang, Rinu Maniyara, Chengye Dong, Joshua A. Robinson, Vincent H. Crespi, Xiaoqin Li, Allan H. MacDonald, Chih-Kang Shih
Summary: Recent research has shown that monolayer Ag confined between bilayer graphene and SiC is a large band gap two-dimensional semiconductor. This conclusion was revealed through the use of time-resolved and angle-resolved photoemission spectroscopy.
Article
Physics, Applied
Qianhui Ren, Takeshi Suzuki, Teruto Kanai, Jiro Itatani, Shik Shin, Kozo Okazaki
Summary: We studied the nonequilibrium electronic structure of 1T-TaS2 using time- and angle-resolved photoemission spectroscopy. Strong photoexcitation leads to the collapse of the Mott gap and induces a photo-induced metallic phase. The oscillation of photoemission intensity is found to be caused by coherent phonons corresponding to the amplitude mode of the charge density wave. By analyzing the frequency-domain angle-resolved photoemission spectroscopy, we observe anti-phase oscillation between two peak structures, which are attributed to the minimum and maximum band positions in energy synchronizing with the CDW amplitude mode.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Condensed Matter
Maxime Rumo, Aki Pulkkinen, KeYuan Ma, Fabian O. von Rohr, Matthias Muntwiler, Claude Monney
Summary: In this study, full hemispherical x-ray photoelectron diffraction experiments were used to investigate the atomic position changes near the surface of 1T-IrTe2 during a phase transition. The results revealed a break in symmetry and the formation of a staircase-like stacking of dimers in the surface layers of IrTe2.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
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
Multidisciplinary Sciences
Philipp Kurzhals, Geoffroy Kremer, Thomas Jaouen, Christopher W. Nicholson, Rolf Heid, Peter Nagel, John-Paul Castellan, Alexandre Ivanov, Matthias Muntwiler, Maxime Rumo, Bjoern Salzmann, Vladimir N. Strocov, Dmitry Reznik, Claude Monney, Frank Weber
Summary: Electron-phonon coupling is a common phenomenon in solids, leading to emergent ground states such as superconductivity. This study demonstrates that strong phonon broadening can occur in the absence of Fermi surface nesting or lattice anharmonicity, if electron-phonon coupling is enhanced for specific electron momenta. The findings suggest a new mechanism for understanding phonon anomalies in materials.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Physical
Rahul Singh, Shiv Kumar, A. Jain, Mahima Singh, Labanya Ghosh, A. Singh, Soma Banik, A. Lakhani, S. Patil, E. F. Schwier, K. Shimada, S. M. Yusuf, Sandip Chatterjee
Summary: The topological insulators Bi2-xFexSe3-xSx were investigated using various techniques, revealing a negative giant magneto-resistance (MR) effect with parallel electric and magnetic fields under Fe and S doping. The magnetic ordering behavior was explained by both surface and bulk interactions. ARPES study and the presence of quantum oscillations supported the preservation of topological surface properties with co-doping of Fe and S.
JOURNAL OF MATERIOMICS
(2022)
Article
Physics, Condensed Matter
Hitoshi Yamaoka, Eike F. Schwier, Yoshiya Yamamoto, Takuma Kawai, Naohito Tsujii, Naohisa Hirao, Nozomu Hiraoka, Hirofumi Ishii, Jun'ichiro Mizuki
Summary: The hydrostatic pressure dependent evolution of the electronic and magnetic structure of LaCo5 and YCo5 was investigated. The study found a common magnetic transition mechanism in both compounds, where the Fermi-level crossing of an up-spin polarized flat band drives a Lifshitz type transition of the Fermi surface. Additionally, a phase transition in LaCo5 was observed to be caused by the change in the down-spin density of states at the Fermi level.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
Article
Physics, Multidisciplinary
Francesco Petocchi, Christopher W. Nicholson, Bjoern Salzmann, Diego Pasquier, Oleg Yazyev, Claude Monney, Philipp Werner
Summary: We address the problem of the ground state of 1T-TaS2 by studying the correlated electronic structure of stacked bilayers. The surface termination determines whether the uncorrelated system is band insulating or exhibits a metallic surface state. A Mott gap opens in the surface state but is smaller than the gap originating from the bilayer structure. Our results are consistent with recent experimental measurements and clarify the interplay between Mott insulating and band insulating behavior in this system.
PHYSICAL REVIEW LETTERS
(2022)
Review
Chemistry, Physical
Selene Mor, Marc Herzog, Claude Monney, Julia Staehler
Summary: An excitonic insulator phase is formed by the spontaneous formation of electron-hole pairs (excitons) in semiconductors, with higher exciton binding energy than the electronic band gap. Employing a nonequilibrium approach, the photoinduced dynamics of an exciton condensate and the valence band electrons in Ta2NiSe5 were studied. The findings reveal the energy gain of ground state exciton formation and demonstrate the use of time-resolved photoemission to study the re-formation dynamics of an exciton condensate.
PROGRESS IN SURFACE SCIENCE
(2022)
Article
Spectroscopy
Claude Monney, Luc Patthey, Elia Razzoli, Thorsten Schmitt
Summary: In the past 20 years, the RIXS technique has made rapid progress due to advancements in instrumentation, synchrotron technology, and theoretical understanding. This article highlights recent developments in the field and is dedicated to the memory of Professor Jean-Claude Dousse from the University of Fribourg.
X-RAY SPECTROMETRY
(2022)
Article
Multidisciplinary Sciences
Geoffroy Kremer, Julian Maklar, Laurent Nicolai, Christopher W. Nicholson, Changming Yue, Caio Silva, Philipp Werner, J. Hugo Dil, Juraj Krempasky, Gunther Springholz, Ralph Ernstorfer, Jan Minar, Laurenz Rettig, Claude Monney
Summary: α-GeTe(111) is a non-centrosymmetric ferroelectric semiconductor material with a strong spin-orbit interaction and giant Rashba coupling. Its ferroelectric polarization can be controlled by an electric field at room temperature, and research shows that femtosecond light pulses can modulate the Rashba coupling and enhance the lattice distortion on a femtosecond timescale.
NATURE COMMUNICATIONS
(2022)
Article
Physics, Multidisciplinary
Souma Hikami, Shigeyuki Ishida, Akira Iyo, Hiroshi Eisaki, Masashi Arita, Shiv Kumar, Eike F. Schwier, Kennya Shimada, Naurang L. Saini, Takashi Mizokawa
Summary: We investigated the Fermi surface and band structure of CaKFe4As4 and found three hole pockets with a significant expansion around the Gamma point. One of the hole pockets showed a larger area compared to previous studies, resulting in degraded Fermi surface nesting. Additionally, the inner hole band shifted downwards and touched the Fermi level at the Gamma point.
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2022)
Article
Materials Science, Multidisciplinary
Bjorn Salzmann, Elina Hujala, Catherine Witteveen, Baptiste Hildebrand, Helmuth Berger, Fabian O. von Rohr, Christopher W. Nicholson, Claude Monney
Summary: The transition-metal dichalcogenide tantalum disulphide (1T-TaS2) exhibits a commensurate charge density wave (CCDW) phase below 165 K. This CCDW phase can be transformed into a metastable metallic mosaic phase by laser or voltage pulses. In this study, scanning tunneling microscopy and spectroscopy (STM/STS) were used to observe the occurrence of the metallic mosaic phase on the surface of TaS2 without prior pulse excitation. Surface defects are believed to contribute to the formation of a dense domain wall network, which is responsible for the metallic behavior in the mosaic phase.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Anup Pradhan Sakhya, Shiv Kumar, Arindam Pramanik, Ram Prakash Pandeya, Rahul Verma, Bahadur Singh, Sawani Datta, Souvik Sasmal, Rajib Mondal, Eike F. Schwier, Kenya Shimada, A. Thamizhavel, Kalobaran Maiti
Summary: Studied the behavior of nontrivial Dirac fermion states in the antiferromagnetic metal SmBi. Experimental results showed the existence of multiple Fermi pockets and band inversion. In addition, Dirac cones were found within the energy gap of the bulk bands. The Fermi surface constituted by the surface states was destroyed near the Néel temperature.
Article
Materials Science, Multidisciplinary
A. Estyunin, E. F. Schwier, S. Kumar, K. Shimada, K. Kokh, O. E. Tereshchenko, A. M. Shikin
Summary: Contemporary studies of magnetic topological insulators require accurate measurements to investigate Dirac point gaps. In this study, the effect of band energy shift due to sample contamination and irradiation on electronic structure measurement using ARPES method is examined. The results show that the shifted topological surface state remains stable and can be used to store information, but it becomes significantly broadened and its intensity drops under irradiation.
Article
Materials Science, Multidisciplinary
Shailja Sharma, Shiv Kumar, Girish C. Tewari, Girish Sharma, Eike F. Schwier, Kenya Shimada, A. Taraphder, C. S. Yadav
Summary: The researchers conducted magnetotransport and ARPES measurements on PdxBi2Te3 single crystals and discovered the reduction of magnetoresistance and mobility upon Pd doping, as well as the presence of TSSs confirmed by SdH oscillations. Hall measurement and ARPES measurements also revealed the change in charge carrier type and band structure induced by Pd doping.
Article
Materials Science, Multidisciplinary
M. Puppin, C. W. Nicholson, C. Monney, Y. Deng, R. P. Xian, J. Feldl, S. Dong, A. Dominguez, H. Hubener, A. Rubio, M. Wolf, L. Rettig, R. Ernstorfer
Summary: This work extends the band structure mapping to the unoccupied states and the entire Brillouin zone by using a state-of-the-art light source to probe optically excited samples. The wideranging applicability and power of this approach are demonstrated, providing direct access to the energy-momentum dispersion of the excited-state spectral function.