Anisotropic distortion and Lifshitz transition inα-Hf under pressure

Abstract

In this work we report a theoretical investigation on behavior of the elastic constant C 44 and the transverse optical phonon mode E 2g of α-Hf under pressure within the density functional theory. In contrast to many other reported transition metals, the above two quantities do not show a synchronous relation as pressure increases. Below 13 GPa, an opposite shifting tendency has been observed. However, once the pressure is raised above 13 GPa, the trend is pulled back to be consistent. This anomalous behavior is figured out to be caused by the large lattice anisotropy of the c/a ratio along with the elastic anisotropy. The synchronous behavior is found to be in accordance with the behavior of c/a ratio with increased pressure. In our band-structure investigations the electronic topological transition has been discovered at 10 GPa, which relates to the change of c/a ratio suggested by recent literature. The presence of the Van Hove singularity shown in the densities of states has been identified and regarded as the origin of the variation of C 44 and E 2g .

Emergence of topological electronic phases in elemental lithium under pressure

“…4 (d) -(f) as it evolves from a single loop centered at Γ to a double loop centered at the Y point. A Lifshitz transition was initially suggested to occur in metals under pressure (34); while it has been observed experimentally in heavier elements (36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47), we predict it to occur in lithium as well.…”

A novel two-dimensional superconducting Ti layer: density functional theory and electron-beam irradiation

“…Such a change in FS clearly brings about an electronic topological transition (ETT). 48,49 It is emphasized that approximately in the middle of X-G, the smaller FS sheets in the corners almost disappear, allowing for another occurrence of ETT. A band structure and FS with an expanded k-path have been added, as shown in Fig.…”

An Ab Initio Investigation of CdSnN2 Under Uniaxial Compressions

“…As shown in literatures, in some cases, applying stress or strain can effectively manipulate the electronic structure and mechanical properties of materials. [ 21–28 ] As for the II–IV–V 2 ceramics, it was recently discovered that XGeN 2 (X = Mg,Zn,Cd) and MSnN 2 (M = Mg,Zn) transit from structure to Pnma structure under uniaxial compression along [100] direction at a certain value, [ 19,29,30 ] where MgGeN 2 and MgSnN 2 can stabilize at the newly discovered Pnma phase after fully removing the compression. Based on this, thickness‐dependent thin films were constructed and studied on their electronic properties.…”