Single-component molecular conductor [Pt(dmdt)2]—a three-dimensional ambient-pressure molecular Dirac electron system

2019 ◽  
Vol 55 (23) ◽  
pp. 3327-3330 ◽  
Author(s):  
Biao Zhou ◽  
Shoji Ishibashi ◽  
Tatsuru Ishii ◽  
Takahiko Sekine ◽  
Ryosuke Takehara ◽  
...  

[Pt(dmdt)2], an air-stable single-component molecular conductor, contains massless Dirac electrons and carries Dirac nodal lines at ambient pressure.

2021 ◽  
Vol 103 (3) ◽  
Author(s):  
Shunsuke Kitou ◽  
Takao Tsumuraya ◽  
Hikaru Sawahata ◽  
Fumiyuki Ishii ◽  
Ko-ichi Hiraki ◽  
...  

2017 ◽  
Vol 139 (5) ◽  
pp. 1770-1773 ◽  
Author(s):  
Reizo Kato ◽  
HengBo Cui ◽  
Takao Tsumuraya ◽  
Tsuyoshi Miyazaki ◽  
Yoshikazu Suzumura

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 534
Author(s):  
Hengbo Cui ◽  
Hamish H.-M. Yeung ◽  
Yoshitaka Kawasugi ◽  
Takaaki Minamidate ◽  
Lucy K. Saunders ◽  
...  

A single-component molecular crystal [Pd(dddt)2] has been shown to exhibit almost temperature-independent resistivity under high pressure, leading theoretical studies to propose it as a three-dimensional (3D) Dirac electron system. To obtain more experimental information about the high-pressure electronic states, detailed resistivity measurements were performed, which show temperature-independent behavior at 13 GPa and then an upturn in the low temperature region at higher pressures. High-pressure single-crystal structure analysis was also performed for the first time, revealing the presence of pressure-induced structural disorder, which is possibly related to the changes in resistivity in the higher-pressure region. Calculations based on the disordered structure reveal that the Dirac cone state and semiconducting state coexist, indicating that the electronic state at high pressure is not a simple Dirac electron system as previously believed. Finally, the first measurements of magnetoresistance on [Pd(dddt)2] under high pressure are reported, revealing unusual behavior that seems to originate from the Dirac electron state.


2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Wei Luo ◽  
Yuma Nakamura ◽  
Jinseon Park ◽  
Mina Yoon

AbstractRecent experiments identified Co3Sn2S2 as the first magnetic Weyl semimetal (MWSM). Using first-principles calculation with a global optimization approach, we explore the structural stabilities and topological electronic properties of cobalt (Co)-based shandite and alloys, Co3MM’X2 (M/M’ = Ge, Sn, Pb, X = S, Se, Te), and identify stable structures with different Weyl phases. Using a tight-binding model, for the first time, we reveal that the physical origin of the nodal lines of a Co-based shandite structure is the interlayer coupling between Co atoms in different Kagome layers, while the number of Weyl points and their types are mainly governed by the interaction between Co and the metal atoms, Sn, Ge, and Pb. The Co3SnPbS2 alloy exhibits two distinguished topological phases, depending on the relative positions of the Sn and Pb atoms: a three-dimensional quantum anomalous Hall metal, and a MWSM phase with anomalous Hall conductivity (~1290 Ω−1 cm−1) that is larger than that of Co2Sn2S2. Our work reveals the physical mechanism of the origination of Weyl fermions in Co-based shandite structures and proposes topological quantum states with high thermal stability.


2018 ◽  
Vol 86 (2) ◽  
pp. 479-492 ◽  
Author(s):  
Siqi Liu ◽  
Xiezhen Zhou ◽  
Weiqing Han ◽  
Jiansheng Li ◽  
Xiuyun Sun ◽  
...  

Author(s):  
Zipeng Guo ◽  
Lu An ◽  
Sushil Lakshmanan ◽  
Jason Armstrong ◽  
Shenqiang Ren ◽  
...  

Abstract The macro-porous ceramics has promising durability and thermal insulation performance. As porous ceramics find more and more applications across many industries, a cost-effective and scalable additive manufacturing technique for fabricating macro-porous ceramics is highly desirable. Herein, we reported a facile additive manufacturing approach to fabricate porous ceramics and control the printed porosity. Several printable ceramic inks were prepared, the foaming agent was added to generate gaseous bubbles in the ink, followed by the direct ink writing and the ambient-pressure and room-temperature drying to create the three-dimensional geometries. A set of experimental studies were performed to optimize the printing quality. The results revealed the optimal process parameters for printing the foamed ceramic ink with a high spatial resolution and fine surface quality. Varying the concentration of the foaming agent enables the controllability of the structural porosity. The maximum porosity can reach 85%, with a crack-free internal porous structure. The tensile tests showed that the printed macro-porous ceramics possessed enhanced durability with the addition of fiber. With a high-fidelity 3D printing process and the precise controllability of the porosity, we showed that the printed samples exhibited a remarkably low thermal conductivity and durable mechanical strength.


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