arXiv subjects

Yanfeng Ge

Publications and source records attributed to Yanfeng Ge.

60 records · Page 4Linked to original sources

arXiv2018

High phonon-limited mobility of BAs under pressure

Recent experiment reports that high thermal conductivity of ~1000 W/mK is observed in cubic boron arsenide crystal (BAs). In order to expand the scope of future applications, we use first-principles calculations to investigate the phonon-limited electronic transport in BAs family and modulation effect of pressure. In the case of electron doping, BAs, AlAs and AlSb exhibit the coupling between high frequency optical phonons and electron as well as the low frequency acoustical phonons in BSb. And BAs has the weakest electron-phonon coupling thus has a high N-type carrier mobility of 1740 cm^2/Vs. After the introduction of pressure, phonon spectra has more obvious change than the electronic structure. The phonon hardening under the pressure gives rise to the weakening of electron-phonon coupling. It is obtained that the pressure of 50 GPa can improve the mobility of BAs up to 4300 cm^2/Vs, which is much high and great significance to the current semiconductor industry.

cond-mat.mtrl-sci↗

arXiv2018

Type-I and type-II Nodal Lines Coexistence in the Antiferromagnetic monolayer CrAs$_{2}$

Topological nodal line semimetals, hosting one-dimensional Fermi lines with symmetry protection, has become a hot topic in topological quantum matter. Due to the breaking of time reversal symmetry in magnetic system, nodal lines require protection by additional symmetries. Here, we report the discovery of antiferromagnetic type-I and type-II nodal lines coexist in the monolayer CrAs$_{2}$ based on a systematic first-principles calculation. Remarkably, the type-I nodal line in CrAs$_{2}$ form a concentric loop centered around the $Γ$ point is filling-enforced by nonsymmorphic analogue symmetry and robust against spin-orbital coupling. The type-II nodal lines, a kind of open nodal lines appear around the Fermi level, are protected by the mirror symmetry in the absence of spin-orbital coupling. The antiferromagnetic monolayer CrAs$_{2}$ proposed here may provide a platform for the correlation between magnetism and exotic topological phases.

cond-mat.mtrl-sci↗

arXiv2016

A new kind of 2D topological insulators BiCN with a giant gap and its substrate effects

Based on DFT calculation, we predict that BiCN, i.e., bilayer Bi films passivated with -CN group, is a novel 2D Bi-based material with highly thermodynamic stability, and demonstrate that it is also a new kind of 2D TI with a giant SOC gap (? 1 eV) by direct calculation of the topological invariant Z2 and obvious exhibition of the helical edge states. Monolayer h-BN and MoS2 are identified as good candidate substrates for supporting the nontrivial topological insulating phase of the 2D TI films, since the two substrates can stabilize and weakly interact with BiCN via van derWaals interaction and thus hardly affect the electronic properties, especially the band topology. The topological properties are robust against the strain and electric field. This may provide a promising platform for realization of novel topological phases.

cond-mat.mes-hall↗

arXiv2016

Possible Superconductivity Approaching Ice Point

Recently BCS superconductivity at 203 K has been discovery in a highly compressed hydrogen sulfide. We use first-principles calculations to systematically examine the effects of partially substituting the chalcogen atoms on the superconductivity of hydrogen chalcogenides under high pressures. We find detailed trends of how the critical temperature changes with increasing the V-, VI- or VII-substitution rate, which highlight the key roles played by low atomic mass and by strong covalent metallicity. In particular, a possible record high critical temperature of 280 K is predicted in a stable H3S0.925P0.075 with the Im-3m structure under 250 GPa.

cond-mat.supr-con↗

arXiv2014

Effect of modulations of doping and strain on the electron transport in monolayer MoS_2

The doping and strain effects on the electron transport of monolayer MoS_2 are systematically investigated using the first-principles calculations with Boltzmann transport theory. We estimate the mobility has a maximum 275 cm^2/(Vs) in the low doping level under the strain-free condition. The applying a small strain (3%) can improve the maximum mobility to 1150 cm^2/(Vs) and the strain effect is more significant in the high doping level. We demonstrate that the electric resistance mainly due to the electron transition between K and Q valleys scattered by the M momentum phonons. However, the strain can effectively suppress this type of electron-phonon coupling by changing the energy difference between the K and Q valleys. This sensitivity of mobility to the external strain may direct the improving electron transport of MoS_2.

cond-mat.mtrl-sci↗

arXiv2013

Phonon-mediated Superconductivity in Silicene

We predict that electron-doped silicene is a good two-dimensional electron-phonon superconductor under biaxial tensile strain by first-principles calculations within rigid band approximation. Superconductivity transition temperature of electron-doped silicene can be increased to be above 10 K by 5% tensile strain. Band structures, phonon dispersive relations, and Eliashberg functions are calculated for detailed analysis. The strong interaction between acoustic phonon modes normal to the silicene plane and the increasing electronic states around the Fermi level induced by tensile strain is mainly responsible for the enhanced critical temperature.

cond-mat.supr-con↗