Endless Dirac nodal lines in kagome-metal Ni3In2S2

TL;DR

This paper predicts and confirms the existence of endless Dirac nodal lines in the kagome-metal Ni3In2S2, revealing a complex topological electronic structure with significant magnetoresistance.

Contribution

It introduces the discovery of multiple endless Dirac nodal lines and rings in Ni3In2S2 using first-principles calculations and experimental validation.

Findings

Six endless nodal lines along stacking direction

Two nodal rings in kagome plane

Large magnetoresistance up to 2000% at 9 T

Abstract

Topological semimetals are a frontier of quantum materials. In multi-band electronic systems, topological band-crossings can form closed curves, known as nodal lines. In the presence of spin-orbit coupling and/or symmetry-breaking operations, topological nodal lines can break into Dirac/Weyl nodes and give rise to novel transport properties, such as the chiral anomaly and giant anomalous Hall effect. Recently the time-reversal symmetry-breaking induced Weyl fermions are observed in a kagome-metal Co3Sn2S2, triggering interests in nodal-line excitations in multiband kagome systems. Here, using first-principles calculations and symmetry based indicator theories, we find six endless nodal lines along the stacking direction of kagome layers and two nodal rings in the kagome plane in nonmagnetic Ni3 In2 S2 . The linear dipsersive electronic structure, confirmed by angle-resolved photoemission spectroscopy, induces large magnetoresistance up to 2000% at 9 T. Our results establish a diverse topological landscape of multi-band kagome metals.