Electron-doped magnetic Weyl semimetal LixCo3Sn2S2 by bulk-gating

TL;DR

This study demonstrates bulk-gating in a magnetic Weyl semimetal, achieving significant electron doping and Fermi level shifts via Li intercalation, expanding the scope of gate control in quantum materials.

Contribution

It introduces a method to modulate carrier density in bulk crystals using ionic gating, with detailed analysis of Li intercalation effects in Co3Sn2S2.

Findings

Li intercalation exceeds 5×10²¹ cm⁻³ electron doping

Fermi energy shifts by 200 meV due to doping

Carrier-dependent anomalous Hall conductivity matches DFT predictions

Abstract

Manipulating carrier density through gate effects, both in electrostatic charge storage and electrochemical intercalation mode, offers powerful control over material properties, although commonly restricted to ultra-thin films or van der Waals materials. Here we demonstrate the application of gate-driven carrier modulation in the microdevice of magnetic Weyl semimetal Co3Sn2S2, fabricated from a bulk single crystal via focused ion beam (FIB). We discovered a Li-intercalated phase LixCo3Sn2S2 featuring electron doping exceeding 5*1021 cm-3, resulting in the Fermi energy shift of 200 meV. The carrier density dependent anomalous Hall conductivity shows fair agreement with density functional theory (DFT) calculation, which also predicts intercalated Li+ ion stabilization within the anion layer while maintaining the kagome-lattice intact. This likely explains the observed rigid band behavior and constant Curie temperature, contrasting with magnetic site substitution experiments. Our findings suggest ionic gating on FIB devices broadens the scope of gate-tuning in quantum materials.