Article
Physics, Multidisciplinary
Pin-Wen Guan, Ying Sun, Russell J. Hemley, Hanyu Liu, Yanming Ma, Venkatasubramanian Viswanathan
Summary: Researchers evaluated the feasibility of synthesizing ternary Li-Mg superhydrides using the pressure-potential method and found that appropriate electrode potentials can stabilize Li2MgH16 and Li4MgH24 at modest pressures. Three structural forms of Li2MgH16 were observed below 300 GPa, with the highest pressure phase exhibiting superconductivity.
PHYSICAL REVIEW LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Rhine Samajdar, Yanting Teng, Mathias S. Scheurer
Summary: This study explores lattice relaxation and long-wavelength phonon modes of twisted trilayer graphene, revealing different phonon modes with varying symmetries and discussing the effects of symmetry breaking on the system.
Article
Chemistry, Physical
Ya-Le Tao, Wei Zeng, Juan Gao, Zheng-Tang Liu, Zhen Jiao, Qi-Jun Liu
Summary: The metallization of alkaline earth metal hydrides offers a path towards achieving near-room temperature superconductivity. Through first-principles calculations, we investigate the properties and the metallization mechanisms of dihydrides and tetrahydrides of alkaline earth metals. Under applied pressure, the structures of these hydrides undergo phase transitions, and the size of the bandgap decreases until it eventually closes. Our findings suggest that MgH4-I4/mmm has the potential to be a high-temperature superconductor and provide new ideas for the search of unknown high-temperature superconducting materials.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Ya-Le Tao, Wei Zeng, Juan Gao, Zheng-Tang Liu, Zhen Jiao, Qi-Jun Liu
Summary: This study systematically investigates the property changes and metallization mechanism of alkaline earth metal hydrides based on first-principles calculations. It is found that external pressure can induce structural phase transitions and decrease or close the bandgap of these hydrides. The formation of hydrogen units accelerates the metallization process and promotes the realization of high superconducting transition temperature. The theoretical findings suggest that MgH4-I4/mmm has the potential to be a high-temperature superconductor and provide new ideas for the search of unknown high-temperature superconducting materials.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Yanfeng Ge, Kun Luo, Yong Liu, Guochun Yang, Wentao Hu, Baozhong Li, Guoying Gao, Xiang-Feng Zhou, Bo Xu, Zhisheng Zhao, Yongjun Tian
Summary: The search for new high-temperature superconductors and understanding their superconducting mechanism is crucial in condensed matter physics. The discovery of near-room temperature superconductivity at high pressure opens up possibilities for finding similar superconductivity at ambient pressure. Carbon materials, with their structural diversity and electronic adjustability, have the potential to exhibit high-temperature superconductivity.
MATERIALS TODAY PHYSICS
(2022)
Article
Engineering, Mechanical
Soon Kim, Sung Youb Kim
Summary: The study discovered that dislocation mobility in FCC crystals at ultralow temperatures is influenced by the dislocation oscillation mode and drag mechanism, rather than material properties. This suggests that the description of FCC crystal plasticity might be consistent at ultralow temperatures, independent of materials.
INTERNATIONAL JOURNAL OF PLASTICITY
(2021)
Article
Multidisciplinary Sciences
Sun-Woo Kim, Lewis J. Conway, Chris J. Pickard, G. Lucian Pascut, Bartomeu Monserrat
Summary: Nitrogen-doped lutetium hydride, recently proposed as a superconductor at near-ambient conditions, features distinct color changes from blue to pink to red as a function of pressure. Using theoretical calculations, the authors identify the pink phase as hydrogen-deficient LuH2 and find that this phase is not a phonon-mediated superconductor near room temperature. Further, the color is controlled by the concentration of hydrogen vacancies.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Multidisciplinary
Imran Saeed, Hyuk Kyu Pak, Tsvi Tlusty
Summary: The concept of quasiparticles helps to explain various quantum phenomena in solids. It has been shown that certain properties of a classical system of hydrodynamically interacting particles can also be described by means of quasiparticles.
Article
Materials Science, Multidisciplinary
Kevin K. Ly, David M. Ceperley
Summary: The high-temperature superconductor LaH10 adopts a face-centered cubic structure under pressures greater than 100 GPa. Upon decompression, a distortion occurs, but superconductivity is still maintained at a lower critical temperature. Quantum effects and anharmonic effects are necessary to stabilize the cubic structure, and a rhombohedral distortion appears at low pressures.
Article
Materials Science, Multidisciplinary
N. Pellatz, S. Roy, J-W Lee, J. L. Schad, H. Kandel, N. Arndt, C. B. Eom, A. F. Kemper, D. Reznik
Summary: Time-resolved measurements provide a new way to unravel complex interactions in quantum materials, as demonstrated in our study using pump-probe Raman scattering to investigate apical oxygen vibration in YBa2Cu3O6+x. The time dependence of the phonon population showed strong electron-phonon coupling, and the phonon energy shift to a higher level due to transient smearing of the Fermi surface, in agreement with theoretical predictions. Insights into photoinduced superconductivity reported at lower doping can be drawn from these results.
Article
Materials Science, Multidisciplinary
Jia Guo, Chenhui Zhang, Weizheng Liang, Xi-Xiang Zhang, S. N. Luo
Summary: In this study, the strong enhancement of coherent phonon excitation in Fe3GeTe2 via the resonance Raman effect was reported. The maximum coherent phonon excitation at a specific pump photon energy was found to be directly related to an electronic transition in Fe3GeTe2. Our work demonstrates that the resonance Raman effect can effectively enhance coherent phonon excitation through electronic excitation.
Article
Materials Science, Multidisciplinary
Chi-Cheng Lee, Ji-Yao Chiu, Yukiko Yamada-Takamura, Taisuke Ozaki
Summary: The study reveals that the LTLO phase in La2-xSrxCuO4 is the ground state, with structural phase transitions driven by phonon instability. The LTLO phase is proposed to be intimately related to the observed pseudogap and charge-density wave.
Article
Materials Science, Multidisciplinary
Hulei Yu, Yue Chen
Summary: In this study, the doping effects on newly proposed penta-graphene-like hydrides ZrH10 and HfH10 were explored using first-principles calculations. It was found that hole doping eliminates the imaginary phonon frequencies of P63/mmc ZrH10 and HfH10 at lower pressures, leading to more accessible superconductivity. On the other hand, electron doping softens the phonons at high pressures, increasing the electron-phonon coupling and the superconducting critical temperature (Tc).
Article
Materials Science, Multidisciplinary
Shuang-Xing Zhu, Chen Zhang, Qi-Yi Wu, Xiao-Fang Tang, Hao Liu, Zi-Teng Liu, Yang Luo, Jiao-Jiao Song, Fan-Ying Wu, Yin-Zou Zhao, Shu-Yu Liu, Tian Le, Xin Lu, He Ma, Kai-Hui Liu, Ya-Hua Yuan, Han Huang, Jun He, H. Y. Liu, Yu-Xia Duan, Jian-Qiao Meng
Summary: The study on 1T-TiTe2 material revealed the existence of a kink and a flat band, which are more pronounced at low temperatures and become blurred as temperature rises. Ultrafast optical spectroscopy identified multiple distinct time scales, with significant responses to temperature variations.
Article
Chemistry, Physical
Roman Lucrezi, Simone Di Cataldo, Wolfgang von der Linden, Lilia Boeri, Christoph Heil
Summary: This study reports the theoretical prediction of two high-performing hydride superconductors BaSiH8 and SrSiH8, including their stability and critical temperature predictions, as well as a method to estimate the lowest pressure of synthesis.
NPJ COMPUTATIONAL MATERIALS
(2022)
Article
Physics, Condensed Matter
H. Y. Uzunok, Ertugrul Karaca, S. Bagci, H. M. Tutuncu
SOLID STATE COMMUNICATIONS
(2020)
Article
Chemistry, Inorganic & Nuclear
H. M. Tutuncu, Ertugrul Karaca, H. Y. Uzunok, S. Bagci, G. P. Srivastava
SOLID STATE SCIENCES
(2020)
Article
Materials Science, Multidisciplinary
H. Y. Uzunok, H. M. Tutuncu, Ertugrul Karaca, G. P. Srivastava
PHILOSOPHICAL MAGAZINE
(2020)
Article
Chemistry, Multidisciplinary
H. Y. Uzunok, A. El-Hajj, H. M. Tutuncu, Ertugrul Karaca, G. P. Srivastava
Summary: This study elucidates the impact of spin-orbit coupling on the physical properties and superconductivity of ternary Laves compound Mg2Ir3Si through full relativistic and scalar relativistic calculations. The inclusion of SOC decreases electron-phonon coupling strength and subsequently lowers the superconducting transition temperature.
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
(2021)
Article
Materials Science, Multidisciplinary
S. Bagci, H. Y. Uzunok, Israa A. Al-Chalabi, H. M. Tutuncu
Summary: In this paper, the properties of orthorhombic MoRuP were analyzed using density functional theory, revealing its mechanical stability and classification as a traditional BCS-type superconductor with strong coupling. The superconductivity mechanism of MoRuP involves the coupling of Mo 4d electrons with lattice vibrations.
PHILOSOPHICAL MAGAZINE
(2021)
Article
Physics, Applied
S. Saib, H. Y. Uzunok, Ertugrul Karaca, S. Bagci, H. M. Tutuncu, G. P. Srivastava
Summary: Ab initio pseudopotential calculations were conducted to study the structural, electronic, elastic, mechanical, and electron-phonon interaction properties of molybdenum borocarbide (Mo2BC) and niobium boronitride (Nb2BN) superconductors. It was found that the bonding nature in both compounds is a combination of covalent, ionic, and metallic, with significant differences in electronic states and density of states at the Fermi level. The calculated superconducting transition temperatures were comparable to experimental values for both compounds.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Chemistry, Physical
E. Karaca, P. J. P. Byrne, P. J. Hasnip, H. M. Tutuncu, M. I. J. Probert
Summary: The superconducting transition temperatures Tc of hexagonal Nb(2)AC (A: Al, S, Ge, As and Sn) were investigated using density functional perturbation theory to model the electron-phonon interaction. The results suggest that Nb2AlC may have the highest Tc among the materials studied, with superconductivity potentially being driven by the interactions of Nb 4d-state electrons with low-frequency phonons.
ELECTRONIC STRUCTURE
(2021)
Article
Physics, Condensed Matter
E. Karaca, S. Bagci, M. Tepecinar, H. Y. Uzunok, H. M. Tutuncu
Summary: This theoretical study investigates the superconductivity of Ta3Ge by examining its various properties. The results show that Ta3Ge has high elasticity, and the transition metal d states and vibrations play a crucial role in the transition to the superconducting state. The calculated superconducting temperature is in good agreement with experimental values.
SOLID STATE COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
H. Y. Uzunok, H. M. Tutuncu, S. Bagci
Summary: We have investigated the impact of spin-orbit coupling (SOC) in cubic Laves superconductors AIr2 (A = Y, Lu, and Th) by using ab initio pseudopotential calculations. The inclusion of SOC removes the degeneracy of electronic states and moderately affects the elastic and mechanical properties. The compounds studied are soft due to significant metallic bonding. The influence of SOC on phonon and electron-phonon interaction properties depends on the type of A element, and it improves the agreement with experimental results for the superconducting transition temperatures.
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
(2023)
Article
Physics, Condensed Matter
A. El-Hajj, H. Y. Uzunok, H. M. Tutuncu, E. Karaca, G. P. Srivastava
Summary: We have conducted a first-principles investigation on the impact of spin-orbit coupling (SOC) on the physical properties and superconductivity of noncentrosymmetric hexagonal superconductors T7B3 (T = Ru and Re). The influence of SOC on electronic, elastic, and mechanical properties is slightly larger for Re7B3 compared to Ru7B3 due to the higher nuclear charge of Re. Transition metal-related phonon modes contribute over 90% to the electron-phonon coupling parameter. SOC has a slightly more significant effect on the Eliashberg spectral function of Re7B3, increasing the electron-phonon coupling parameter by around 3.0%, while it decreases by less than 1.0% for Ru7B3. Consequently, SOC increases the superconducting transition temperature of Re7B3 from 2.20 K to 2.51 K and decreases that of Ru7B3 from 4.34 K to 3.79 K.
PHYSICA B-CONDENSED MATTER
(2023)
Article
Physics, Multidisciplinary
Sadik Bagci, Halime Yarar, Huseyin Yasin Uzunok
Summary: This research investigates the role of spin-orbit coupling (SOC) in compounds of ATl(3) (A = Ca, Y, La, and Th) and La3Tl, examining their structural, electronic, elastic, mechanical, phonon, and electron-phonon interaction properties. The results show that SOC affects the electronic band structures by removing degeneracies that exist in a scalar relativistic calculation without SOC. The replacement of La and Tl atoms in LaTl3 increases the density of states at the Fermi level and makes the phonon modes softer, resulting in stronger electron-phonon interaction. SOC also increases the Tc values of LaTl3 and ThTl3, improving agreement with experimental values.
ANNALEN DER PHYSIK
(2023)