Layer-Number-Dependent Metal-Insulator Transition in Topological Semimetal Nb₃SiTe₆

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Topologically nontrivial materials possess inherent robustness against perturbations.
• The stability of topological degeneracies against electronic instabilities is not well understood.

Purpose of the Study:

• Investigate the resilience of topological degeneracies in Nb3SiTe6 against electronic instabilities.
• Explore the layer-number-dependent metal-insulator transitions in this topological semimetal.

Main Methods:

• Transport measurements to observe electrical properties.
• Electrostatic gating to tune electronic behavior.
• Theoretical calculations to understand underlying mechanisms.

Main Results:

• Demonstrated a layer-number-dependent metal-insulator transition in Nb3SiTe6.
• Observed an insulating ground state in monolayers, tunable by gating.
• Found that ambipolar gating behavior contradicts single-particle picture predictions.
• Identified electronic instabilities as a plausible mechanism for gap opening.

Conclusions:

• Electronic instabilities can drive metal-insulator transitions in topological materials, even at protected nodal lines.
• Findings offer insights into dimension-related transitions in topological semimetals.