Magnetic, transport and topological properties of Co-based shandite thin films

TL;DR

This study provides detailed ab initio analysis of Co3Sn2S2 thin films, revealing that Sn-terminated films maintain large, quantized anomalous Hall effects similar to the bulk, while Co-layer number significantly influences properties.

Contribution

First comprehensive ab initio investigation of Co3Sn2S2 thin films, demonstrating stable ferromagnetism and quantized AHE in Sn-terminated monolayers, guiding experimental exploration of thin Weyl materials.

Findings

Sn-end films stabilize ferromagnetism similar to bulk

Large AHE persists down to monolayer, quantized in Sn-terminated films

Magnetic and topological properties vary with Co-layer number in S-end films

Abstract

The kagome ferromagnet, Co-based shandite Co3Sn2S2, shows a large anomalous Hall effect (AHE) associated with the Weyl nodes. A thin film with a Co kagome monolayer was predicted to exhibit the quantum AHE, which awaits the experimental realisation. However, it is challenging to precisely predict how the Weyl nodes reside in thin films where the lattice and electronic structures are in general different from the bulk. Here we report comprehensive ab initio results for thin films of Co3Sn2S2 with one, two and three Co layers with Sn or S surface terminations. We find that all the Sn-end films stabilise a ferromagnetic state similar to the bulk, and retain the large AHE down to the monolayer limit where the AHE is quantised, while the magnetic and topological properties drastically change with the number of Co layers in the S-end films. Our results would stimulate further experimental exploration of thin Weyl materials.