Lifshitz transitions and elastic properties of Osmium under pressure

TL;DR

This study uses density functional calculations to identify Lifshitz transitions in Osmium under high pressure, revealing weak elastic anomalies and clarifying previous experimental inconsistencies.

Contribution

It provides the first theoretical evidence of multiple Lifshitz transitions in Osmium at high pressures and analyzes their impact on elastic properties.

Findings

Osmium undergoes three Lifshitz transitions between 70 GPa and 130 GPa.

Elastic anomalies related to these transitions are very weak and difficult to detect.

Pressure dependence of the c/a ratio can be modeled smoothly without significant anomalies.

Abstract

Topological changes of the Fermi surface under pressure may cause anomalies in the low-temperature elastic properties. Our density functional calculations for elemental Osmium evidence that this metal undergoes three such Lifshitz transitions in the pressure range between 70 GPa and 130 GPa. The related elastic anomalies are, however, invisibly weak. The critical pressures considerably exceed the values for recently measured and calculated anomalies in the pressure (P) dependence of the hexagonal c/a lattice parameter ratio close to 25 GPa. We demonstrate that the latter anomalies are statistically not significant and that (c/a)(P) can be fitted equally well by a smooth dependence.