Nuclear magnetic resonance at up to 10.1 Giga-Pascal pressure detects an electronic topological transition in aluminum metal

TL;DR

This study uses high-pressure $^{27}$Al NMR to detect an electronic topological transition in aluminum at 10.1 GPa, revealing deviations from free electron behavior and symmetry changes.

Contribution

It provides direct NMR evidence of a Lifshitz transition in aluminum under high pressure, linking electronic structure changes to pressure-induced phenomena.

Findings

Detection of negative curvature in electronic density of states with pressure

Observation of a Lifshitz transition at 10.1 GPa

Increase in NMR linewidth indicating symmetry change

Abstract

High-sensitivity $^{27}$Al nuclear magnetic resonance (NMR) measurements of aluminum metal under hydrostatic pressure of up to 10.1 GPa reveal an unexpected negative curvature in the pressure-dependence of the electronic density of states measured through shift and relaxation, which violates free electron behavior. A careful analysis of the Fermiology of aluminum shows that pressure induces an electronic topological transition (Lifshitz transition) that is responsible for the measured change in the density of states. The experiments also reveal a sudden increase in the NMR linewidth above 4.2 GPa from quadrupole interaction, which is not in agreement with the metal's cubic symmetry.