Characteristic singular behaviors of nodal line materials emerging in orbital magnetic susceptibility and Hall conductivity

TL;DR

This paper investigates the unique singular behaviors of orbital magnetic susceptibility and Hall conductivity in nodal line materials, revealing characteristic delta and step function responses that depend on chemical potential and magnetic field orientation.

Contribution

It introduces a formalism using thermal Green's functions to identify singular behaviors in nodal line materials' magnetic and transport properties, aiding experimental detection.

Findings

Orbital magnetic susceptibility exhibits a delta-function singularity near the nodal line.

Hall conductivity shows a step function behavior as a function of chemical potential.

Singular behaviors depend strongly on the magnetic field angle and nodal line orientation.

Abstract

The bulk properties of nodal line materials have been an important research topic in recent years. In this paper, we study the orbital magnetic susceptibility and the Hall conductivity of nodal line materials using the formalism with thermal Green's functions and find characteristic singular behaviors of them. It is shown that, in the vicinity of the gapless nodal line, the orbital magnetic susceptibility shows a $\delta$-function singularity and the Hall conductivity shows a step function behavior in their chemical potential dependences. Furthermore, these singular behaviors are found to show strong field angle dependences corresponding to the orientation of the nodal line in the momentum space. These singular behaviors and strong angle dependences will give clear evidence for the presence of the nodal line and its orientation and can be used to experimentally detect nodal line materials.