Raman signature of cation vacancies in rare-earth nitrides

TL;DR

This study combines Raman spectroscopy and computational analysis to identify cation vacancies in rare-earth nitrides, revealing a vibrational mode linked to these vacancies that could enable hole doping in these ferromagnetic semiconductors.

Contribution

It introduces a Raman signature for cation vacancies in rare-earth nitrides, providing a new method to detect and potentially control defect-related properties.

Findings

Raman-active mode at 1100-1400 cm$^{-1}$ signals cation vacancies.

Mode frequency matches computed breathing vibrations around vacancies.

Presence of vacancies suggests new doping possibilities for rare-earth nitrides.

Abstract

We report a coordinated Raman/computation study of the rare-earth nitrides, a series of intrinsic ferromagnetic semiconductors, to reveal the presence of cation vacancies. Their presence is signaled by a Raman-active vibrational mode at 1100-1400 cm$^{-1}$, rising steadily as the lattice contracts across the series. The mode's frequency is in excellent agreement with the computed breathing-mode vibration of the six nitrogen ions surrounding cation vacancies. The discovery of such cation vacancies opens the door for hole doping that has so far been lacking in the exploitation of rare-earth nitrides.