arXiv subjects

Jiesen Li

Publications and source records attributed to Jiesen Li.

5 recordsLinked to original sources

arXiv2021

Strain-induced topological phase transition in two-dimensional platinum ditelluride

Topological phase transition is a hot topic in condensed matter physics and computational material science. Here, we investigate the electronic structure and phonon dispersion of the two-dimensional (2D) platinum ditelluride ($PtTe_2$) using the density functional theory. It is found that the $PtTe_2$ monolayer is a trivial insulator with an indirect band gap of 0.347eV. Based on parity analysis, the biaxial tensile strain can drive the topological phase transition. As the strain reaches 19.3%, $PtTe_2$ undergoes a topological phase transition, which changes from a trivial band insulator to a topological insulator with $Z_2=1$. Unlike conventional honeycomb 2D materials with topological phase transition, which gap closes at K points, the strained $PtTe_2$ monolayer becomes gapless at M points under critical biaxial strain. The band inversion leads the switch of the parities near the Fermi level, which gives rise to the topological phase transition. The novel monolayer $PtTe_2$ has a potential application in the field of micro-electronics.

cond-mat.mtrl-sci↗

arXiv2020

Phonon dispersions and electronic structures of two-dimensional IV-V compounds

One novel family of two-dimensional IV-V compounds have been proposed, whose dynamical stabilities and electronic properties have been systematically investigated using the density functional theory. Extending from our previous work, two phases of carbon phosphorus bilayers α- and β-C$_{2}$P$_{2}$ have been proposed. Both of them are dynamically stable and thermally stable at 300K. They possess intrinsic HSE gaps of 2.70 eV and 2.67 eV, respectively. Similar α- and β-C$_{2}$Y$_{2}$ (Y= As, Sb, and Bi) can be obtained if the phosphorus atoms in the α- and β-C$_{2}$P$_{2}$ replaced by other pnictogens, respectively. If the C atoms in the α- and β-C$_{2}$Y$_{2}$ (Y= P, As, Sb, and Bi) are further replaced by other IV elements X (X=Si, Ge, Sn, and Pb), respectively, more derivatives of α- and β-X$_{2}$Y$_{2}$ (Y=N, P, As, Sb, and Bi) also can be obtained. It was found that the majority of them are dynamically stable. The proposed compounds range from metal to insulators depending on their constitutions. All insulated compounds can undergo a transition from insulator to metal induced by biaxial strain. Some of them can undergo a transition from indirect band gap to direct band gap. These new compounds can become candidates as photovoltaic device, thermoelectric material field as well as lamellated superconductors.

cond-mat.mtrl-sci↗

arXiv2017

Stabilities and novel electronic structures of three carbon nitride bilayers

Three new novel phases of carbon nitride (CN) bilayer, which are named as α-C$_{2}$N$_{2}$, β-C$_{2}$N$_{2}$ and γ-C$_{4}$N$_{4}$, respectively, have been predicted in this paper. All of them are consisted of two CN sheets connected by C-C covalent bonds. The phonon dispersions reveal that all these phases are dynamically stable, since no imaginary frequency is found for them. Transition path way between α-C$_{2}$N$_{2}$ and β-C$_{2}$N$_{2}$ is investigated, which involves bond-breaking and bond-reforming between C and N. This conversion is difficult, since the activation energy barrier is found to be 1.90 eV per unit cell, high enough to prevent the transformation at room temperature. Electronic structures calculations show that they are all semiconductors with indirect band gap of 3.76 / 5.22 eV, 4.23 / 5.75 eV and 2.06 / 3.53 eV by PBE / HSE calculation, respectively. The β-C$_{2}$N$_{2}$ has the widest band gap among the three phases. From our results, the three new two-dimensional materials have potential applications in the electronics, semiconductors, optics and spintronics.

cond-mat.mtrl-sci↗

arXiv2017

Electronic Structure and Band Gap Engineering of Two-Dimensional Octagon-Nitrogene

We have predicted a new phase of nitrogen with octagon structure in our previous study, which we referred to as octa-nitrogene (ON). In this work, we make further investigation on its electronic structure. The phonon band structure has no imaginary phonon modes, which indicates that ON is dynamically stable. Using ab initio molecular dynamic simulations, the structure is found to stable up to 100K, and ripples that are similar to that of graphene is formed on the ON sheet. Based on DFT calculation on its band structure, single layer ON is a 2D large-gap semiconductor with a band gap of 4.7eV. Because of inter-layer interaction, stackings can decrease the band gap. Biaxial tensile strain and perpendicular electric field can greatly influence the band structure of ON, in which the gap decreases and eventually closes as the biaxial tensile strain or the perpendicular electric field increases. In other words, both biaxial tensile strain and perpendicular electric field can drive the insulator-to-metal transition, and thus can be used to engineer the band gap of ON. From our results, ON has potential applications in the electronics, semiconductors, optics and spintronics, and so on.

cond-mat.mtrl-sci↗

arXiv2017

Phonon and electronic properties of semiconducting silicon nitride bilayers

The two-dimensional (2D) IV-V semiconductors have attracted much attention due to their fascinating electronic and optical properties. In this work, we predicted three phases of silicon nitrides, denoted $\alpha$-Si$_{2}$N$_{2}$, $\beta$-Si$_{2}$N$_{2}$, and $\gamma$-Si$_{4}$N$_{4}$, respectively. Both $\alpha$-Si$_{2}$N$_{2}$ and $\beta$-Si$_{2}$N$_{2}$ consist of two buckled SiN sheets, and $\gamma$-Si$_{4}$N$_{4}$ consists of two puckered SiN sheets. It is challenging to transform between $\alpha$-Si$_{2}$N$_{2}$ and $\beta$-Si$_{2}$N$_{2}$ because of the high energy barrier. The three dynamically stable bilayers are semiconductors with fundamental indirect band gaps from 0.25 eV to 2.92 eV. As expected, only the s and p orbitals contribute to the electronic states, and the pz orbitals dominate near the Fermi level. Furthermore, insulator-metal transitions occur in $\alpha$-Si$_{2}$N$_{2}$ and $\beta$-Si$_{2}$N$_{2}$ under the biaxial strain of 16%. These materials perhaps have potential applications in microelectronics and spintronics.

cond-mat.mtrl-sci↗