Orbital-dependent quasiparticle scattering interference in 3R-NbS2

TL;DR

This study combines experimental QPI imaging and theoretical simulations to reveal how orbital degrees of freedom influence quasiparticle scattering in 3R-NbS2, impacting valley transport properties.

Contribution

It demonstrates the dominant role of orbital degrees of freedom in quasiparticle scattering processes in 3R-NbS2, linking orbital structure to valley scattering behavior.

Findings

Inter-valley QPI signal is weaker than intra-valley signal.

Orbital degrees of freedom primarily influence scattering behavior.

Findings enhance understanding of valley-related transport in transition metal dichalcogenides.

Abstract

A valley degree of freedom (DOF) in transition metal dichalcogenides with broken inversion symmetry can be controlled through spin and orbital DOFs owing to their valley-contrasting characters. Another important aspect of the spin and orbital DOFs is that they affect quasiparticle scattering processes that govern the valley lifetime. Here we combine quasiparticle-interference (QPI) imaging experiments and theoretical simulations to study the roles of the spin and orbital DOFs in 3R-NbS2. We find that the QPI signal arising from an inter-valley scattering is noticeably weaker than that caused by an intra-valley scattering. We show that this behavior is predominantly associated with the orbital DOF, signifying the different spin and orbital structures of spin-split bands at each valley. These findings provide important insights into understanding the valley-related transport properties.