Quantum oscillation in Hopf-link semimetals

TL;DR

This paper proposes using quantum oscillation measurements in strong magnetic fields to identify Hopf-link topological semimetals by analyzing phase shifts in Fermi pockets, aiding experimental detection of complex topologies.

Contribution

It introduces a method to detect Hopf-link topological semimetals through quantum oscillation phase shifts, providing a practical approach for experimental identification.

Findings

Distinct phase shift patterns depend on magnetic field orientation.

Self-consistent analysis of Fermi surface and Landau levels supports the method.

Potential application to real materials like Li₂NaN.

Abstract

Since the discovery of the relation between the Chern number and quantum Hall effect, searching for observables of topological invariants has been an intriguing topic. Topological Hopf-link semimetals have attracted tremendous interest, in which the conduction and valence energy bands touch at linked nodal lines. However, it is challenging to identify this sophisticated topology. We propose to use the quantum oscillation in strong magnetic fields to probe the Hopf links. For a generic model of Hopf-link semimetal that captures the linked-trivial phase transition, we figure out the phase shifts of oscillation for all Fermi pockets in all magnetic-field directions, by presenting self-consistent results from the Fermi surface tomography, Landau fan diagram, and electrical resistivity. As the magnetic field is rotated, the phase shifts exhibit a unique pattern, which could help to identify Hopf links in real materials, such as those in Li$_2$NaN.