Article
Chemistry, Physical
G. M. Whyte, C. Awada, P. O. Offor, F. U. Whyte, M. B. Kanoun, S. Goumri-Said, A. Alshoaibi, A. B. C. Ekwealor, M. Maaza, Fabian Ezema
Summary: This study investigates the influence of rare-earth oxide (Yb2O3) on arsenic selenide (As-Se) host through electrodeposition technique, studying nanocomposite films' structural, optical, morphological, and electronic features. Results showed Yb addition affecting the host matrix's structure and properties, with potential applications in phase-change memory and solar cells.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Materials Science, Multidisciplinary
Ting-Yun Hsieh, Babu Baijnath Prasad, Guang-Yu Guo
Summary: This paper investigates the intrinsic spin Hall effect (SHE) and spin Nernst effect (SNE) in the CoSi family of transition metal monosilicides, and discovers their unconventional chiral fermion semimetals possess unique chiral structures and large spin Hall and spin Nernst conductivities.
Article
Chemistry, Physical
Yongzhen Chen, Sarbani Ghosh, Xianjie Liu, Igor Zozoulenko, Mats Fahlman, Slawomir Braun
Summary: The evolution of the electronic structure and optical transition in n-doped poly(9,9-dioctylfluorene) (PFO) films was studied using photoelectron spectroscopy, optical absorption, density functional theory (DFT), and time-dependent DFT calculations. Experimental results showed various absorption features and changes in electronic states upon doping, which were interpreted by theoretical calculations. This study provides insights into the effects of doping on the electronic properties of PFO films.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Nanoscience & Nanotechnology
Asish K. Kundu, Genda Gu, Tonica Valla
Summary: Bismuth materials in Bi(110) films exhibit intriguing electronic structure properties, with the experimental verification of theoretical predictions providing insights for applications in quantum spin hall effects and beyond.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Multidisciplinary Sciences
Jia-nan Liu, Xu Yang, Haopu Xue, Xue-song Gai, Rui Sun, Yang Li, Zi-Zhao Gong, Na Li, Zong-Kai Xie, Wei He, Xiang-Qun Zhang, Desheng Xue, Zhao-Hua Cheng
Summary: With decreasing thickness of topological insulator thin films, single-particle band theory is insufficient to explain their band structures. This study reconstructs the surface-state coupling in ultrathin films using screened Coulomb interaction and finds that the magnitude of the mass gap agrees well with experimental results.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Paul Dreher, Wen Wan, Alla Chikina, Marco Bianchi, Haojie Guo, Rishav Harsh, Samuel Manas-Valero, Eugenio Coronado, Antonio J. Martinez-Galera, Philip Hofmann, Jill A. Miwa, Miguel M. Ugeda
Summary: The study reveals that the CDW and superconducting states in single-layer NbSe2 exhibit different behaviors on different substrates, with these electronic phases remaining stable on graphene and boron nitride substrates but severely weakened or even absent on metallic substrates.
Article
Physics, Applied
N. N. Kovaleva, D. Chvostova, O. Pacherova, A. Muratov, L. Fekete, I. A. Sherstnev, K. Kugel, F. A. Pudonin, A. Dejneka
Summary: Ultrathin [Bi(0.6-2.5 nm)-FeNi(0.8,1.2 nm)](N) multilayer films were studied using wideband spectroscopic ellipsometry, revealing that the surface metallic conductivity of the Bi layer is strongly influenced by the morphology and magnetic properties of the nanoisland FeNi layer.
APPLIED PHYSICS LETTERS
(2021)
Review
Materials Science, Multidisciplinary
Zaiba Zafar, Sha-Sha Yi, Jin-Peng Li, Chuan-Qi Li, Yong-Fa Zhu, Amir Zada, Wei-Jing Yao, Zhong-Yi Liu, Xin-Zheng Yue
Summary: This review discusses the impact of defect architecture on photocatalytic activity and emphasizes the importance of defect engineering in the design of modern photocatalysts. By tuning the electronic microstructure and surface morphologies of semiconductors, efficiency of photocatalysts can be improved.
ENERGY & ENVIRONMENTAL MATERIALS
(2022)
Article
Instruments & Instrumentation
X. D. Zhu, E. K. Ko, G. Kimbell, J. Robinson
Summary: Sagnac interferometry is advantageous in measuring time-reversal-symmetry breaking effects in ferromagnetic and antiferromagnetic materials. By optimizing the returning optical power, the sensitivity of Sagnac interferometry is maximized, leading to an increase in the signal-to-noise ratio.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2022)
Article
Engineering, Electrical & Electronic
A. Soussi, A. Ait Hssi, M. Boujnah, L. Boulkadat, K. Abouabassi, A. Asbayou, A. Elfanaoui, R. Markazi, A. Ihlal, K. Bouabid
Summary: The electronic, optical, and electrical properties of rutile and anatase phases of titanium dioxide were investigated using first-principles calculations and experimental methods. Both theoretical and experimental results showed differences in band gaps for the two phases. TiO2 exhibited high optical transmission and refractive index in the visible region, which was consistent with the theoretical calculations.
JOURNAL OF ELECTRONIC MATERIALS
(2021)
Article
Chemistry, Physical
Noussiaba Adala, Basma Marzougui, Youssef Ben Smida, Riadh Marzouki, Mounir Ferhi, Damian C. Onwudiwe, Ahmed Hichem Hamzaoui
Summary: This study reports the synthesis and characterization of PrAsO4 polycrystals. The crystal structure was determined using the Rietveld method and validated using the bond valence sum and charge distribution methods. The compound was found to be a direct band gap semiconductor material with good thermal stability and photoluminescent properties. However, it exhibited poor ionic conductivity and dielectric properties.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Chemistry, Physical
Leonid Skripnikov, Dmitry Chubukov, Vera M. Shakhova
Summary: Studying transition energies of heavy-atom alkaline earth monofluoride molecules can simplify the preparation and interpretation of experiments by incorporating quantum electrodynamics (QED) effects. The deviation of calculated values from experimental ones is significantly small, and the importance of QED effects on transition energies is comparable to high-order correlation effects.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Daniel H. Suzuki, Manuel Valvidares, Pierluigi Gargiani, Mantao Huang, Alexander E. Kossak, Geoffrey S. D. Beach
Summary: Rare-earth transition-metal thin films show promise for spintronic applications, but the change in their magnetic properties with composition and thickness needs further quantification. Using x-ray magnetic circular dichroism, this study investigates the atomic magnetic moments of few-nanometer-thick GdCo and TbCo films and finds a decrease in RE and Co average moments with increasing RE concentration. The saturation magnetization is found to be affected by temperature and thickness, with the existence of an intrinsic unalloyed RE dead layer at room temperature reducing the effective RE concentration in the remaining alloyed region.
Article
Chemistry, Multidisciplinary
Timothy E. Kidd, Jacob Weber, Evan O'Leary, Andrew James Stollenwerk
Summary: This study explores a recently discovered class of electronic growth systems in which metal films are grown on the relatively inert surfaces of van der Waals crystals. The electronic growth in this class of materials is highly stable at room temperature and actually requires higher temperature annealing to achieve proper equilibrium.
Article
Chemistry, Multidisciplinary
Wen Wan, Paul Dreher, Daniel Munoz-Segovia, Rishav Harsh, Haojie Guo, Antonio J. Martinez-Galera, Francisco Guinea, Fernando de Juan, Miguel M. Ugeda
Summary: This study reports the existence of a soft collective mode in single-layer NbSe2, observed as a characteristic resonance excitation in high-resolution tunneling spectra. The frequency and amplitude of this resonance change with temperature and magnetic field, establishing a direct link to the superconducting state.
ADVANCED MATERIALS
(2022)
Article
Physics, Multidisciplinary
Jianwei Huang, Rong Yu, Zhijun Xu, Jian-Xin Zhu, Ji Seop Oh, Qianni Jiang, Meng Wang, Han Wu, Tong Chen, Jonathan D. Denlinger, Sung-Kwan Mo, Makoto Hashimoto, Matteo Michiardi, Tor M. Pedersen, Sergey Gorovikov, Sergey Zhdanovich, Andrea Damascelli, Genda Gu, Pengcheng Dai, Jiun-Haw Chu, Donghui Lu, Qimiao Si, Robert J. Birgeneau, Ming Yi
Summary: The underlying mechanism of iron-based superconductivity and the role of electron correlations have been debated since their discovery. This study uses angle resolved photoemission spectroscopy to investigate the Fermi surface reconstruction in FeTe1-xSex and provides evidence for an orbital-selective Mott transition driven by orbital-dependent correlation effects.
COMMUNICATIONS PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Xiaoqian Zhang, Wenqing Liu, Wei Niu, Qiangsheng Lu, Wei Wang, Ali Sarikhani, Xiaohua Wu, Chunhui Zhu, Jiabao Sun, Mitchel Vaninger, Paul F. Miceli, Jianqi Li, David J. Singh, Yew San Hor, Yue Zhao, Chang Liu, Liang He, Rong Zhang, Guang Bian, Dapeng Yu, Yongbing Xu
Summary: This research reports a method to engineer antiferromagnetic magnets in an ultra-high vacuum-free condition. By introducing interstitial Cr atoms in the vdW gaps, interlayer antiferromagnetic coupling is achieved, leading to giant magnetoresistance effect and switching between states at moderate magnetic fields. This work provides a new approach for studying 2D magnetism and constructing low-power devices.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Qiangsheng Lu, Congcong Le, Xiaoqian Zhang, Jacob Cook, Xiaoqing He, Mohammad Zarenia, Mitchel Vaninger, Paul F. Miceli, David J. Singh, Chang Liu, Hailang Qin, Tai-Chang Chiang, Ching-Kai Chiu, Giovanni Vignale, Guang Bian
Summary: This study proposes a new method to achieve flat band physics in monolayer graphene by substrate modulation. Experimental results on the graphene/SiC heterostructure demonstrate that substrate modulation leads to Dirac fermion cloning and the proximity of the two Dirac cones in monolayer graphene. Theoretical modeling confirms the cloning mechanism and predicts the emergence of moire flat bands at certain magic lattice constants of the substrate. This study suggests that epitaxial single monolayer graphene on suitable substrates is a promising platform for exploring exotic many-body quantum phases arising from interactions between Dirac electrons.
ADVANCED MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Qile Li, Chi Xuan Trang, Weikang Wu, Jinwoong Hwang, David Cortie, Nikhil Medhekar, Sung-Kwan Mo, Shengyuan A. Yang, Mark T. Edmonds
Summary: Combining magnetism and nontrivial band topology can achieve the quantum anomalous Hall (QAH) effect at high temperatures for lossless transport applications. In this study, a heterostructure consisting of two single-septuple layers (1SL) of MnBi2Te4, an ultrathin few quintuple layer (QL) Bi2Te3, and another 1SL MnBi2Te4 was grown via molecular beam epitaxy. The electronic structure was probed using angle-resolved photoelectron spectroscopy, and strong hexagonally warped massive Dirac fermions and a bandgap of 75 +/- 15 meV were observed. The magnetic origin of the gap was confirmed, and these findings provide insights into magnetic proximity effects in topological insulators and a promising platform for realizing the QAH effect at elevated temperatures.
ADVANCED MATERIALS
(2022)
Article
Chemistry, Physical
R. Mazza Alessandro, Miettinen Anna, Gai Zheng, He Xiaoqing, R. Charlton Timothy, Z. Ward Thomas, Conrad Matthew, Bian Guang, H. Conrad Edward, Paul F. Miceli
Summary: Modifying the properties of graphene, such as inducing ferromagnetism, has attracted wide interest. This study investigated the interaction between protons and graphene, the mechanism of ferromagnetism induction, and whether protons remain in graphene. The results show that implanted hydrogen remains chemisorbed in graphene and the interlayer expansion is caused by carbon interstitials rather than remaining hydrogen. The magnetic moment is related to the amount of interstitial carbon, indicating that room-temperature ferromagnetism arises from disrupted carbon bonding.
Article
Materials Science, Multidisciplinary
Sean Howard, Arjun Raghavan, Davide Iaia, Caizhi Xu, David Flototto, Man-Hong Wong, Sung-Kwan Mo, Bahadur Singh, Raman Sankar, Hsin Lin, Tai-Chang Chiang, Vidya Madhavan
Summary: This paper examines a tunable topological system and discovers the crossing of the Dirac point through the Fermi energy at x=0.7. This observation is critical for future topological spintronics applications.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Han Wu, Alannah M. Hallas, Xiaochan Cai, Jianwei Huang, Ji Seop Oh, Vaideesh Loganathan, Ashley Weiland, Gregory T. McCandless, Julia Y. Chan, Sung-Kwan Mo, Donghui Lu, Makoto Hashimoto, Jonathan Denlinger, Robert J. Birgeneau, Andriy H. Nevidomskyy, Gang Li, Emilia Morosan, Ming Yi
Summary: The study reports Dirac nodal line crossings in PtPb4, which arise from the nonsymmorphic symmetry of its crystal structure. The results show that the nodal lines remain gapless in the absence of spin-orbit coupling (SOC), but the SOC lifts the band degeneracy everywhere except at a set of isolated points. However, the observed nodal line has a smaller bandwidth than predicted by density functional theory (DFT).
NPJ QUANTUM MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Yao Li, John W. Bowers, Joseph A. Hlevyack, Meng-Kai Lin, Tai-Chang Chiang
Summary: Epitaxial thin-film heterostructures provide a platform for realizing topological surface states, and the experimental demonstration presented here confirms the formation of emergent topological states in such heterostructures. The results illustrate the rich physics of engineered composite topological systems that may be exploited for nanoscale spintronics applications.
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
Materials Science, Multidisciplinary
Sara Salehitaleghani, Tobias Maerkl, Pawel J. Kowalczyk, Maxime Le Ster, Xiaoxiong Wang, Guang Bian, Tai-Chang Chiang, Simon A. Brown
Summary: We investigated the edge states (ESs) of two-dimensional alpha-bismuthene (alpha-Bi) structures on highly oriented pyrolytic graphite substrates using scanning tunnelling microscopy and scanning tunnelling spectroscopy. ESs were detected at the edges in the 5ML and 7ML thick structures, coinciding with the topographical step edges. However, no ESs were observed in the 3ML structures, and instead, new states resulting from strain-induced modulation of the topology were found far from the topographical edge.
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
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
Materials Science, Multidisciplinary
Joseph A. Hlevyack, Yang-Hao Chan, Meng-Kai Lin, Tao He, Wei-Hsiang Peng, Ellen C. Royal, Mei-Yin Chou, T. -C. Chiang
Summary: Coupling ordinary metals with topological insulators can promote the long-range migration of spin-polarized states. However, when trivial metallic films are placed on topological insulators, both topological and trivial interface states emerge. These interface states can be observed through thickness-dependent band mappings and their spectral weights decay rapidly.
Article
Materials Science, Multidisciplinary
Amarnath Chakraborty, Guang Bian, Giovanni Vignale
Summary: This study calculates the optical absorption spectra of nonsymmorphic semimetals and finds that the absorption coefficient strongly depends on the anisotropy factor and photon polarization. In the presence of a magnetic field, the absorption coefficient also depends on the mixing angle of the band structure. Furthermore, it is discovered that an in-plane magnetic field can induce a Van Hove singularity in the joint density of states, enhancing the optical absorption in one direction of polarization but not the other.