Visualization of electronic topology in ZrSiSe by scanning tunneling microscopy

TL;DR

This study uses scanning tunneling microscopy to directly observe the electronic topological features of ZrSiSe, including the nodal line and surface states, advancing understanding of topological semimetals for spintronics.

Contribution

The paper provides the first direct STM evidence of the nodal-line state and surface Dirac point in ZrSiSe, confirming theoretical predictions.

Findings

Nodal line at ~250 meV above Fermi level

Surface Dirac point at ~400 meV below Fermi level

Verification of glide mirror symmetry in ZrSe bilayer

Abstract

As emerging topological nodal-line semimetals, the family of ZrSiX (X = O, S, Se, Te) has attracted broad interests in condensed matter physics due to their future applications in spintonics. Here, we apply a scanning tunneling microscopy (STM) to study the structural symmetry and electronic topology of ZrSiSe. The glide mirror symmetry is verified by quantifying the lattice structure of the ZrSe bilayer based on bias selective topographies. The quasiparticle interference analysis is used to identify the band structure of ZrSiSe. The nodal line is experimentally determined at $\sim$ 250 meV above the Fermi level. An extra surface state Dirac point at $\sim$ 400 meV below the Fermi level is also determined. Our STM measurement provides a direct experimental evidence of the nodal-line state in the family of ZrSiX.