Symmetry driven spin anisotropic magnetotransport in quantum spin Hall insulator WTe2 1T

TL;DR

This study reveals how nonsymmorphic symmetries in monolayer 1T WTe2 cause anisotropic spin-dependent magnetotransport, with edge states showing direction-dependent spin splitting and conductance behavior, relevant for spintronic applications.

Contribution

It provides direct transport evidence of nonsymmorphic-symmetry-protected spin degeneracy and anisotropic magnetotransport in 1T WTe2, highlighting symmetry's role in spin behavior.

Findings

Edge y-ribbons show significant spin splitting and angular conductance dependence.

Edge x-ribbons exhibit negligible spin splitting due to nonsymmorphic symmetry protection.

Bulk states are largely insensitive to magnetic field orientation.

Abstract

We present a comprehensive magnetotransport analysis of monolayer 1T WTe2, highlighting the role of nonsymmorphic symmetries in governing edge-state spin behavior. By comparing the electronic transmission in nanoribbons with edges along the crystallographic y and x directions, our analysis reveals a pronounced anisotropy in the magnetic field response. The y-edge ribbon exhibits significant spin splitting of edge-state bands in both energy and momentum space, along with a strong angular dependence of the conductance. The observed magnetotransport response indicates a spin quantization axis that aligns with the out-of-plane spin quantization axis reported in previous experimental studies. In contrast, the x edge ribbon shows negligible spin splitting under magnetic fields, which is attributed to nonsymmorphic symmetries such as glide mirror and screw rotation, that protects degeneracies along the Gamma X direction, even when time-reversal symmetry is broken. The energy-resolved current density and angular transmission analyses confirm that this anisotropy originates from edge states, while bulk states remain largely insensitive to the field orientation. Our results establish direct transport-spectroscopy based evidence of nonsymmorphic-symmetry-protected spin degeneracy in the 1T WTe2, and underscores its promise for spintronic devices that leverage symmetry-protected and directionally selective transport channels.