Anomalous nuclear magnetic resonance spectra in Bi$_2$Se$_3$ nanowires

TL;DR

This study investigates the $^{209}$Bi NMR spectra of Bi$_2$Se$_3$ nanowires and single crystals, revealing an unusual suppression of signal intensity potentially linked to surface current screening effects.

Contribution

It provides the first comparison of NMR spectra between nanowires and powdered crystals, highlighting unique surface current effects in nanostructures.

Findings

Nanowire spectra match randomly oriented powders.

Unusual signal suppression depends on magnetic field orientation.

Potential surface current screening identified.

Abstract

We report $^{209}$Bi nuclear magnetic resonance (NMR) spectra of in nanowires and single crystals of Bi$_2$Se$_3$. Crystals were powdered to simulate the random orientation of the nanowires, and the spectra are compared with theoretical expectations derived via an orientational study of a single crystal. The nanowire spectra are consistent with the randomly oriented powders, however we find an unusual suppression of signal intensity as a function of field orientation that may be associated with screening by surface currents.