拓扑晶体绝缘体SnTe中压力诱导的相变及其与半导体SnSe的比较：拉曼和第一性原理研究,Physical Review B

当前位置： X-MOL 学术 › Phys. Rev. B › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

拓扑晶体绝缘体SnTe中压力诱导的相变及其与半导体SnSe的比较：拉曼和第一性原理研究
Physical Review B ( IF 3.2 ) Pub Date : 2020-04-10 , DOI: 10.1103/physrevb.101.155202
Sukanya Pal , Raagya Arora , Subhajit Roychowdhury , Luminita Harnagea , Kumar Saurabh , Sandhya Shenoy , D. V. S. Muthu , Kanishka Biswas , U. V. Waghmare , A. K. Sood

SnTe是一种窄带隙拓扑晶体绝缘体（TCI），而SnSe是一种普通的半导体。我们报告了SnTe和SnSe作为室温下压力的函数的拉曼研究，以及第一原理密度泛函理论计算。在压力下，SnTe中观察到同构转变，最强拉曼模态异常软化到1.5 GPa都显示出这一现象，同时线宽增加。我们的第一性原理计算表明，SnTe的镜像Chern数不变，并且TCI相仍不受压力的影响。其在1.5 GPa的相变的拉曼信号与声子的不稳定性有关。

Γ

点和最低能量导带的反演。电子-声子耦合中的异常导致在该压力下拉曼模式的异常行为。此外，SnTe在

〜 5.8 ， 〜 12

和

〜 18.3 GPa

。5.8-GPa转变与周围立方的结构转变有关（ $F 米 \bar{3} 米$ ）到正交的（Pnma）相，后者不再是拓扑绝缘体，从而导致拓扑相变。高于12 GPa的转变压力时，另一个正交晶Pnma [GeS]相稳定下来，与Pnma相共存。上面观察到的拉曼模式数量减少

〜 18.3 GPa

和焓的计算表明从斜方（Pnma）到对称的立方（Pnma）过渡。

下午 \bar{3} 米

）结构体。另一方面，我们对SnSe的高压研究表明，它经历了两个相变：一个从斜方晶（Pnma）结构到斜方晶（Cmcm）结构。

〜 6.2 GPa

另一个在

〜 12.9 GPa

，其中Cmcm相经历从半金属到金属的过渡。密度泛函理论计算捕获了拓扑晶体绝缘子SnTe和常规半导体SnSe在压力相关行为中的反差。

"点击查看英文标题和摘要"

Pressure-induced phase transitions in the topological crystalline insulator SnTe and its comparison with semiconducting SnSe: Raman and first-principles studies

SnTe is a narrow band-gap topological crystalline insulator (TCI), whereas SnSe is a normal semiconductor. We report Raman study of SnTe and SnSe as a function of pressure at room temperature along with first-principles density functional theory calculations. Under pressure, isostructural transition is observed in SnTe, as revealed by the anomalous softening of the strongest Raman mode up to 1.5 GPa, accompanied by an increase in the linewidth. Our first-principles calculations show that the mirror Chern number of SnTe does not change and the TCI phase remains unaffected by pressure. Raman signatures of its phase transition at 1.5 GPa are associated with phonon instability at the

Γ

point and inversion of the lowest-energy conduction bands. An anomaly in the electron-phonon coupling results in anomalous behavior of the Raman modes at this pressure. Further, SnTe undergoes structural transitions at

\sim 5.8, \sim 12

, and

\sim 18.3 GPa

. The 5.8-GPa transition is associated with a structural transition from the ambient cubic ( $F m \bar{3} m$ ) to orthorhombic (Pnma) phase, which is no longer a topological insulator, resulting in a topological phase transition. Above the transition pressure of 12 GPa, another orthorhombic Pnma[GeS] phase is stabilized, coexisting with the Pnma phase. The reduction in the number of observed Raman modes above

\sim 18.3 GPa

and enthalpy calculations show a transition from orthorhombic (Pnma) to a more symmetric cubic (

Pm \bar{3} m

) structure. Our high-pressure study of SnSe, on the other hand, reveals that it undergoes two phase transitions: one from the orthorhombic (Pnma) structure to the orthorhombic (Cmcm) structure at

\sim 6.2 GPa

and the other at

\sim 12.9 GPa

, in which the Cmcm phase undergoes a semimetal to metal transition. Density functional theory calculations capture the contrast in the pressure-dependent behavior of the topological crystalline insulator SnTe and the normal semiconductor SnSe.

更新日期：2020-04-10

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南