Thin film synthesis, structural analysis, and magnetic properties of novel ternary transition metal nitride <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>MnCoN</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>

Recent high-throughput computational searches have predicted many novel ternary nitride compounds providing new opportunities for materials discovery in underexplored phase spaces. Nevertheless, there are hardly any predictions and/or syntheses that incorporate only transition metals into new ternary nitrides. Here, we report on the synthesis, structure, and properties of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msub><a:mi>MnCoN</a:mi><a:mn>2</a:mn></a:msub></a:math>, a new ternary nitride material comprising only transition metals and N. We find that crystalline <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:msub><b:mi>MnCoN</b:mi><b:mn>2</b:mn></b:msub></b:math> can be stabilized over its competing binaries, and over a tendency of this system to become amorphous, by controlling growth temperature within a narrow window slightly above ambient condition. We find that single-phase <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:msub><c:mi>MnCoN</c:mi><c:mn>2</c:mn></c:msub></c:math> thin films form in a cation-disordered rocksalt crystal structure. X-ray photoelectron spectroscopy analysis suggests that <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:msub><d:mi>MnCoN</d:mi><d:mn>2</d:mn></d:msub></d:math> is sensitive to oxygen through various oxides and hydroxides binding to cobalt on the surface. X-ray absorption spectroscopy is used to verify that <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"><e:msup><e:mrow><e:mi>Mn</e:mi></e:mrow><e:mrow><e:mn>3</e:mn><e:mo>+</e:mo></e:mrow></e:msup></e:math> and <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"><f:msup><f:mrow><f:mi>Co</f:mi></f:mrow><f:mrow><f:mn>3</f:mn><f:mo>+</f:mo></f:mrow></f:msup></f:math> cations exist in an octahedrally coordinated environment, which is distinct from a combination of CoN and MnN binaries and in agreement with the rocksalt-based crystal structure prediction. Magnetic measurements suggest that <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"><g:msub><g:mi>MnCoN</g:mi><g:mn>2</g:mn></g:msub></g:math> has a canted antiferromagnetic ground state below 10 K. We extract a Weiss temperature of <h:math xmlns:h="http://www.w3.org/1998/Math/MathML"><h:mrow><h:mi>θ</h:mi><h:mo>=</h:mo><h:mo>−</h:mo><h:mn>49.7</h:mn><h:mspace width="0.16em"/><h:mi mathvariant="normal">K</h:mi></h:mrow></h:math>, highlighting the antiferromagnetic correlations in <k:math xmlns:k="http://www.w3.org/1998/Math/MathML"><k:msub><k:mi>MnCoN</k:mi><k:mn>2</k:mn></k:msub></k:math>. Published by the American Physical Society 2024