Real-Time Monitoring of Strain Accumulation and Relief during Epitaxy of Ultrathin Co Ferrite Films with Varied Co Content
Ultrathin Co<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mi>x</mi></msub></semantics></math></inline-formula>Fe<inline-formula><mat...
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2023-11-01
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| Online Access: | https://www.mdpi.com/1996-1944/16/23/7287 |
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| author | Jannis Thien Jari Rodewald Tobias Pohlmann Kevin Ruwisch Florian Bertram Karsten Küpper Joachim Wollschläger |
| author_facet | Jannis Thien Jari Rodewald Tobias Pohlmann Kevin Ruwisch Florian Bertram Karsten Küpper Joachim Wollschläger |
| author_sort | Jannis Thien |
| collection | DOAJ |
| description | Ultrathin Co<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mi>x</mi></msub></semantics></math></inline-formula>Fe<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mrow><mn>3</mn><mo>−</mo><mi>x</mi></mrow></msub></semantics></math></inline-formula>O<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>4</mn></msub></semantics></math></inline-formula> films of high structural quality and with different Co content (<i>x</i> = 0.6–1.2) were prepared by reactive molecular beam epitaxy on MgO(001) substrates. Epitaxy of these ferrite films is extensively monitored by means of time-resolved (operando) X-ray diffraction recorded in out-of-plane geometry to characterize the temporal evolution of the film structure. The Co ferrite films show high crystalline ordering and smooth film interfaces independent of their Co content. All Co<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mi>x</mi></msub></semantics></math></inline-formula>Fe<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mrow><mn>3</mn><mo>−</mo><mi>x</mi></mrow></msub></semantics></math></inline-formula>O<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>4</mn></msub></semantics></math></inline-formula> films exhibit enhanced compressive out-of-plane strain during the early stages of growth, which partly releases with increasing film thickness. When the Co content of the ferrite films increases, the vertical-layer distances increase, accompanied by slightly increasing film roughnesses. The latter result is supported by surface-sensitive low-energy electron diffraction as well as X-ray reflectivity measurements on the final films. In contrast, the substrate–film interface roughness decreases with increasing Co content, which is confirmed with X-ray reflectivity measurements. In addition, the composition and electronic structure of the ferrite films is characterized by means of hard X-ray photoelectron spectroscopy performed after film growth. The experiments reveal the expected increasing <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>Fe</mi><mrow><mn>3</mn><mo>+</mo></mrow></msup></semantics></math></inline-formula>/<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>Fe</mi><mrow><mn>2</mn><mo>+</mo></mrow></msup></semantics></math></inline-formula> cation ratios for a higher Co content. |
| first_indexed | 2024-03-09T01:47:33Z |
| format | Article |
| id | doaj.art-0883e07170a34f2a84211d75e987699f |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-09T01:47:33Z |
| publishDate | 2023-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Materials |
| spelling | doaj.art-0883e07170a34f2a84211d75e987699f2023-12-08T15:20:33ZengMDPI AGMaterials1996-19442023-11-011623728710.3390/ma16237287Real-Time Monitoring of Strain Accumulation and Relief during Epitaxy of Ultrathin Co Ferrite Films with Varied Co ContentJannis Thien0Jari Rodewald1Tobias Pohlmann2Kevin Ruwisch3Florian Bertram4Karsten Küpper5Joachim Wollschläger6Department of Physics, Osnabrück University, 49076 Osnabrück, GermanyDepartment of Physics, Osnabrück University, 49076 Osnabrück, GermanyDepartment of Physics, Osnabrück University, 49076 Osnabrück, GermanyDepartment of Physics, Osnabrück University, 49076 Osnabrück, GermanyDeutsches Elektronen-Synchrotron (DESY), Photon Science, 22607 Hamburg, GermanyDepartment of Physics, Osnabrück University, 49076 Osnabrück, GermanyDepartment of Physics, Osnabrück University, 49076 Osnabrück, GermanyUltrathin Co<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mi>x</mi></msub></semantics></math></inline-formula>Fe<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mrow><mn>3</mn><mo>−</mo><mi>x</mi></mrow></msub></semantics></math></inline-formula>O<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>4</mn></msub></semantics></math></inline-formula> films of high structural quality and with different Co content (<i>x</i> = 0.6–1.2) were prepared by reactive molecular beam epitaxy on MgO(001) substrates. Epitaxy of these ferrite films is extensively monitored by means of time-resolved (operando) X-ray diffraction recorded in out-of-plane geometry to characterize the temporal evolution of the film structure. The Co ferrite films show high crystalline ordering and smooth film interfaces independent of their Co content. All Co<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mi>x</mi></msub></semantics></math></inline-formula>Fe<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mrow><mn>3</mn><mo>−</mo><mi>x</mi></mrow></msub></semantics></math></inline-formula>O<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>4</mn></msub></semantics></math></inline-formula> films exhibit enhanced compressive out-of-plane strain during the early stages of growth, which partly releases with increasing film thickness. When the Co content of the ferrite films increases, the vertical-layer distances increase, accompanied by slightly increasing film roughnesses. The latter result is supported by surface-sensitive low-energy electron diffraction as well as X-ray reflectivity measurements on the final films. In contrast, the substrate–film interface roughness decreases with increasing Co content, which is confirmed with X-ray reflectivity measurements. In addition, the composition and electronic structure of the ferrite films is characterized by means of hard X-ray photoelectron spectroscopy performed after film growth. The experiments reveal the expected increasing <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>Fe</mi><mrow><mn>3</mn><mo>+</mo></mrow></msup></semantics></math></inline-formula>/<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>Fe</mi><mrow><mn>2</mn><mo>+</mo></mrow></msup></semantics></math></inline-formula> cation ratios for a higher Co content.https://www.mdpi.com/1996-1944/16/23/7287cobalt ferriteultrathin filmsstrainX-ray diffraction |
| spellingShingle | Jannis Thien Jari Rodewald Tobias Pohlmann Kevin Ruwisch Florian Bertram Karsten Küpper Joachim Wollschläger Real-Time Monitoring of Strain Accumulation and Relief during Epitaxy of Ultrathin Co Ferrite Films with Varied Co Content Materials cobalt ferrite ultrathin films strain X-ray diffraction |
| title | Real-Time Monitoring of Strain Accumulation and Relief during Epitaxy of Ultrathin Co Ferrite Films with Varied Co Content |
| title_full | Real-Time Monitoring of Strain Accumulation and Relief during Epitaxy of Ultrathin Co Ferrite Films with Varied Co Content |
| title_fullStr | Real-Time Monitoring of Strain Accumulation and Relief during Epitaxy of Ultrathin Co Ferrite Films with Varied Co Content |
| title_full_unstemmed | Real-Time Monitoring of Strain Accumulation and Relief during Epitaxy of Ultrathin Co Ferrite Films with Varied Co Content |
| title_short | Real-Time Monitoring of Strain Accumulation and Relief during Epitaxy of Ultrathin Co Ferrite Films with Varied Co Content |
| title_sort | real time monitoring of strain accumulation and relief during epitaxy of ultrathin co ferrite films with varied co content |
| topic | cobalt ferrite ultrathin films strain X-ray diffraction |
| url | https://www.mdpi.com/1996-1944/16/23/7287 |
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