GdWN$_3$ is a Nitride Perovskite

TL;DR

This study experimentally confirms that GdWN$_3$ is a perovskite nitride with antiferromagnetic order, contrasting prior predictions, and explores its synthesis, structure, and initial properties, advancing the understanding of nitride perovskites.

Contribution

It demonstrates the synthesis and structural confirmation of GdWN$_3$ as a perovskite, supported by experimental and theoretical evidence, challenging previous non-perovskite predictions.

Findings

GdWN$_3$ crystallizes in a distorted $Pnma$ perovskite structure.

GdWN$_3$ is paramagnetic with antiferromagnetic correlations at low temperature.

The absorption onset varies with cation stoichiometry.

Abstract

Nitride perovskites $AB$N$_3$ are an emerging and highly under-explored class of materials that are of interest due to their intriguing calculated ferroelectric, optoelectronic, and other functional properties. Incorporating novel $A$-site cations is one strategy to tune and expand such properties; for example, Gd$^{3+}$ is compelling due to its large magnetic moment, potentially leading to multiferroic behavior. However, the theoretically predicted ground state of GdWN$_3$ is a non-perovskite monoclinic structure. Here, we experimentally show that GdWN$_3$ crystallizes in a perovskite structure. High-throughput combinatorial sputtering with activated nitrogen is employed to synthesize thin films of Gd$_{1-x}$W$_{x}$N$_{3-y}$ with low oxygen content within the bulk of the films. Ex-situ annealing crystallizes a polycrystalline perovskite phase in a narrow composition window near $x=1$. LeBail fits of synchrotron grazing incidence wide angle X-ray scattering data are consistent with a perovskite ground-state structure. New density functional theory calculations that included antiferromagnetic configurations confirm that the ground-state structure of GdWN$_3$ is a distorted $Pnma$ perovskite with antiferromagnetic ordering, in contrast to prior predictions. Initial property measurements find that GdWN$_3$ is paramagnetic down to $T=2$ K with antiferromagnetic correlations and that the absorption onset depends on cation stoichiometry. This work provides an important stepping stone towards the rapid expansion of the emerging family of nitride perovskites and towards our understanding of their potential multiferroic properties.