| Summary: | Phase-separated semiconductors containing magnetic nanostructures are relevant systems for the realization of high-density recording media. Here, the controlled strain engineering of Ga<inline-formula><math display="inline"><semantics><mi>δ</mi></semantics></math></inline-formula>FeN layers with Fe<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mi>y</mi></msub></semantics></math></inline-formula>N embedded nanocrystals (NCs) <i>via</i> Al<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mi>x</mi></msub></semantics></math></inline-formula>Ga<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mrow><mn>1</mn><mo>−</mo><mi>x</mi></mrow></msub></semantics></math></inline-formula>N buffers with different Al concentration <inline-formula><math display="inline"><semantics><mrow><mn>0</mn><mo><</mo><msub><mi>x</mi><mi>Al</mi></msub><mo><</mo><mn>41</mn></mrow></semantics></math></inline-formula>% is presented. Through the addition of Al to the buffer, the formation of predominantly prolate-shaped <inline-formula><math display="inline"><semantics><mi>ε</mi></semantics></math></inline-formula>-Fe<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula>N NCs takes place. Already at an Al concentration <inline-formula><math display="inline"><semantics><msub><mi>x</mi><mi>Al</mi></msub></semantics></math></inline-formula>≈ 5% the structural properties—phase, shape, orientation—as well as the spatial distribution of the embedded NCs are modified in comparison to those grown on a GaN buffer. Although the magnetic easy axis of the cubic <inline-formula><math display="inline"><semantics><mi>γ</mi></semantics></math></inline-formula>’-Ga<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mi>y</mi></msub></semantics></math></inline-formula>Fe<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mrow><mn>4</mn><mo>−</mo><mi>y</mi></mrow></msub></semantics></math></inline-formula>N nanocrystals in the layer on the <inline-formula><math display="inline"><semantics><mrow><msub><mi>x</mi><mi>Al</mi></msub><mo>=</mo><mn>0</mn><mo>%</mo></mrow></semantics></math></inline-formula> buffer lies in-plane, the easy axis of the <inline-formula><math display="inline"><semantics><mi>ε</mi></semantics></math></inline-formula>-Fe<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mn>3</mn></msub></semantics></math></inline-formula>N NCs in all samples with Al<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mi>x</mi></msub></semantics></math></inline-formula>Ga<inline-formula><math display="inline"><semantics><msub><mrow></mrow><mrow><mn>1</mn><mo>−</mo><mi>x</mi></mrow></msub></semantics></math></inline-formula>N buffers coincides with the <inline-formula><math display="inline"><semantics><mrow><mo>[</mo><mn>0001</mn><mo>]</mo></mrow></semantics></math></inline-formula> growth direction, leading to a sizeable out-of-plane magnetic anisotropy and opening wide perspectives for perpendicular recording based on nitride-based magnetic nanocrystals.
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