We conducted in-situ high-pressure synchrotron x-ray diffraction(XRD) and electrical transport measurements on Dirac-like semimetal Pd Sn4 in diamond anvil cells with quasi-hydrostatic pressure condition up to 44.5 GP...We conducted in-situ high-pressure synchrotron x-ray diffraction(XRD) and electrical transport measurements on Dirac-like semimetal Pd Sn4 in diamond anvil cells with quasi-hydrostatic pressure condition up to 44.5 GPa–52.0 GPa. The XRD data show that the ambient orthorhombic phase(Ccca) is stable with pressures to 44.5 GPa, and the lattice parameters and unit-cell volume decrease monotonously upon compression. The temperature dependence of the resistance exhibits a metallic conduction and follows a Fermi-liquid behavior below 50 K, both of which keep unchanged upon compression to 52.0 GPa. The magnetoresistance curve at 5 K maintains a linear feature in a magnetic field range of 2.5 T–7 T with increasing pressure to 20.0 GPa. Our results may provide pressure-transport constraints on the robustness of the Dirac fermions.展开更多
The tunneling current in a graphene nanoribbon tunnel field effect transistor(GNR-TFET) has been quantum mechanically modeled. The tunneling current in the GNR-TFET was compared based on calculations of the Dirac-like...The tunneling current in a graphene nanoribbon tunnel field effect transistor(GNR-TFET) has been quantum mechanically modeled. The tunneling current in the GNR-TFET was compared based on calculations of the Dirac-like equation and Schrodinger’s equation. To calculate the electron transmittance, a numerical approach-namely the transfer matrix method(TMM)-was employed and the Launder formula was used to compute the tunneling current. The results suggest that the tunneling currents that were calculated using both equations have similar characteristics for the same parameters, even though they have different values. The tunneling currents that were calculated by applying the Dirac-like equation were lower than those calculated using Schrodinger’s equation.展开更多
Designing new two-dimensional （2D） semiconductors with novel topological characters is highly desirable for further material innovation. We propose a theoretical design of a stable 2D inorganic material, namely, bor...Designing new two-dimensional （2D） semiconductors with novel topological characters is highly desirable for further material innovation. We propose a theoretical design of a stable 2D inorganic material, namely, borane, which is jointly stabilized by traditional B B localized and unique B-H-B delocalized chemical bonds. In borane, the bonding natures along different directions are distinguishing, which lead to huge differences in mechanical strengths of 142.73 and 97.47N/m for a and b directions, respectively. In a unit cell, each hydrogen atom binds to two boron atoms forming a three-center-two-electron （3c-2e） bridge bond B H B. This can be considered as an extension of diborane molecules from OD to 2D. The collaboration of localized and delocalized chemical bonds endows borane with high structural stability, as indicated by its favorable cohesive energy, high mechanical strength, absence of imaginary modes in the phonon spectrum, and moderate melting point. Remarkably, borane has a fascinating electronic property featured with a Dirae-like ring in the electronic band structure. The unique bonding nature and electronic property in borane would attract intensive interests in both theory and experiment.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2018YFA0305700 and 2016YFA0401804)the National Natural Science Foundation of China(Grant Nos.U1632275,11574323,11874362,11704387,and 11804344)+2 种基金the Natural Science Foundation of Anhui Province,China(Grant Nos.1908085QA18,1708085 QA19,and 1808085MA06)the Major Program of Development Foundation of Hefei Center for Physical Science and Technology,China(Grant No.2018ZYFX002)the Users with Excellence Project of Hefei Science Center of the Chinese Academy of Sciences(Grant No.2018HSC-UE012)
文摘We conducted in-situ high-pressure synchrotron x-ray diffraction(XRD) and electrical transport measurements on Dirac-like semimetal Pd Sn4 in diamond anvil cells with quasi-hydrostatic pressure condition up to 44.5 GPa–52.0 GPa. The XRD data show that the ambient orthorhombic phase(Ccca) is stable with pressures to 44.5 GPa, and the lattice parameters and unit-cell volume decrease monotonously upon compression. The temperature dependence of the resistance exhibits a metallic conduction and follows a Fermi-liquid behavior below 50 K, both of which keep unchanged upon compression to 52.0 GPa. The magnetoresistance curve at 5 K maintains a linear feature in a magnetic field range of 2.5 T–7 T with increasing pressure to 20.0 GPa. Our results may provide pressure-transport constraints on the robustness of the Dirac fermions.
基金supported by Hibah Penelitian Berbasi Kompetensi 2018 RISTEKDIKTI Republic of Indonesia
文摘The tunneling current in a graphene nanoribbon tunnel field effect transistor(GNR-TFET) has been quantum mechanically modeled. The tunneling current in the GNR-TFET was compared based on calculations of the Dirac-like equation and Schrodinger’s equation. To calculate the electron transmittance, a numerical approach-namely the transfer matrix method(TMM)-was employed and the Launder formula was used to compute the tunneling current. The results suggest that the tunneling currents that were calculated using both equations have similar characteristics for the same parameters, even though they have different values. The tunneling currents that were calculated by applying the Dirac-like equation were lower than those calculated using Schrodinger’s equation.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61605087 and 61704083the International Postdoctoral Exchange Fellowship Program between JUELICH and OCPC under Grant No 20161001+2 种基金the Natural Science Foundation of Jiangsu Province under Grant No BK20160881the Jiangsu Provincial Natural Science Research Project under Grant No16KJB140010the Science Foundation of Nanjing University of Posts and Telecommunications under Grant No NY215064
文摘Designing new two-dimensional （2D） semiconductors with novel topological characters is highly desirable for further material innovation. We propose a theoretical design of a stable 2D inorganic material, namely, borane, which is jointly stabilized by traditional B B localized and unique B-H-B delocalized chemical bonds. In borane, the bonding natures along different directions are distinguishing, which lead to huge differences in mechanical strengths of 142.73 and 97.47N/m for a and b directions, respectively. In a unit cell, each hydrogen atom binds to two boron atoms forming a three-center-two-electron （3c-2e） bridge bond B H B. This can be considered as an extension of diborane molecules from OD to 2D. The collaboration of localized and delocalized chemical bonds endows borane with high structural stability, as indicated by its favorable cohesive energy, high mechanical strength, absence of imaginary modes in the phonon spectrum, and moderate melting point. Remarkably, borane has a fascinating electronic property featured with a Dirae-like ring in the electronic band structure. The unique bonding nature and electronic property in borane would attract intensive interests in both theory and experiment.
