Wide-Field Kerr Microscopy and Magnetometry on Cr₂Ge₂Te₆ Exfoliated van-der-Waals Flakes
The potential of wide-field magneto-optical Kerr microscopy for the characterisation of low-dimensional van-der-Waals crystals is explored using the example of Cr₂Ge₂Te₆ flakes in the ten nanometers thickness range. Although the magnetic domains with an expected widt...
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2024-01-01
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| author | Ivan Soldatov Burak Ozer Saicharan Aswartham Sebastian Selter Louis Veyrat Bernd Buchner Rudolf Schafer |
| author_facet | Ivan Soldatov Burak Ozer Saicharan Aswartham Sebastian Selter Louis Veyrat Bernd Buchner Rudolf Schafer |
| author_sort | Ivan Soldatov |
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| description | The potential of wide-field magneto-optical Kerr microscopy for the characterisation of low-dimensional van-der-Waals crystals is explored using the example of Cr₂Ge₂Te₆ flakes in the ten nanometers thickness range. Although the magnetic domains with an expected width in the hundred-nanometer range cannot be seen on this material due to the limited lateral resolution, we show that Kerr microscopy is nevertheless a very valuable method for measuring the magnetization loops on selectable thickness regions on the flake. From the loop character one can indirectly infer on the existence or suppression of band domains, which are the equilibrium patterns above a film thickness of about 7nm. We derived this characteristic thickness from the initial susceptibility of the hysteresis loops and used it to estimate the specific domain wall energy to be <inline-formula> <tex-math notation="LaTeX">$2.7\cdot 10^{-\mathrm {4}}$ </tex-math></inline-formula>J/m². We further demonstrate a thickness- and light colour dependent sign inversion of the Kerr signal that is explained by a Fresnel-type depth sensitivity concept. Accordingly, the Kerr contrast is governed by the relative phase of the Kerr amplitude that can be freely adjusted by a rotatable compensator. The compensator is thus the decisive optical element in magneto-optical Kerr magnetometry and microscopy on low-dimensional materials. It needs to be appropriately aligned to avoid a cancelation of the Kerr contrast and to maximise the Kerr signal. |
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| institution | Kabale University |
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| language | English |
| publishDate | 2024-01-01 |
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| spelling | doaj-art-12322dd07eed401dbdc519138923b1a92025-01-08T00:01:49ZengIEEEIEEE Access2169-35362024-01-011218102518104010.1109/ACCESS.2024.350903010771764Wide-Field Kerr Microscopy and Magnetometry on Cr₂Ge₂Te₆ Exfoliated van-der-Waals FlakesIvan Soldatov0https://orcid.org/0000-0002-2911-1842Burak Ozer1https://orcid.org/0000-0003-3626-772XSaicharan Aswartham2Sebastian Selter3https://orcid.org/0000-0002-8250-3861Louis Veyrat4Bernd Buchner5https://orcid.org/0000-0002-3886-2680Rudolf Schafer6https://orcid.org/0000-0002-7332-3711Leibniz Institute for Solid State and Materials Research Dresden, Dresden, GermanyLeibniz Institute for Solid State and Materials Research Dresden, Dresden, GermanyLeibniz Institute for Solid State and Materials Research Dresden, Dresden, GermanyLeibniz Institute for Solid State and Materials Research Dresden, Dresden, GermanyLeibniz Institute for Solid State and Materials Research Dresden, Dresden, GermanyLeibniz Institute for Solid State and Materials Research Dresden, Dresden, GermanyLeibniz Institute for Solid State and Materials Research Dresden, Dresden, GermanyThe potential of wide-field magneto-optical Kerr microscopy for the characterisation of low-dimensional van-der-Waals crystals is explored using the example of Cr₂Ge₂Te₆ flakes in the ten nanometers thickness range. Although the magnetic domains with an expected width in the hundred-nanometer range cannot be seen on this material due to the limited lateral resolution, we show that Kerr microscopy is nevertheless a very valuable method for measuring the magnetization loops on selectable thickness regions on the flake. From the loop character one can indirectly infer on the existence or suppression of band domains, which are the equilibrium patterns above a film thickness of about 7nm. We derived this characteristic thickness from the initial susceptibility of the hysteresis loops and used it to estimate the specific domain wall energy to be <inline-formula> <tex-math notation="LaTeX">$2.7\cdot 10^{-\mathrm {4}}$ </tex-math></inline-formula>J/m². We further demonstrate a thickness- and light colour dependent sign inversion of the Kerr signal that is explained by a Fresnel-type depth sensitivity concept. Accordingly, the Kerr contrast is governed by the relative phase of the Kerr amplitude that can be freely adjusted by a rotatable compensator. The compensator is thus the decisive optical element in magneto-optical Kerr magnetometry and microscopy on low-dimensional materials. It needs to be appropriately aligned to avoid a cancelation of the Kerr contrast and to maximise the Kerr signal.https://ieeexplore.ieee.org/document/10771764/Magnetic domainsmagnetic hysteresismagneto-optical Kerr microscopyMOKE magnetometry2D magnetic materialsvan der Waals materials |
| spellingShingle | Ivan Soldatov Burak Ozer Saicharan Aswartham Sebastian Selter Louis Veyrat Bernd Buchner Rudolf Schafer Wide-Field Kerr Microscopy and Magnetometry on Cr₂Ge₂Te₆ Exfoliated van-der-Waals Flakes IEEE Access Magnetic domains magnetic hysteresis magneto-optical Kerr microscopy MOKE magnetometry 2D magnetic materials van der Waals materials |
| title | Wide-Field Kerr Microscopy and Magnetometry on Cr₂Ge₂Te₆ Exfoliated van-der-Waals Flakes |
| title_full | Wide-Field Kerr Microscopy and Magnetometry on Cr₂Ge₂Te₆ Exfoliated van-der-Waals Flakes |
| title_fullStr | Wide-Field Kerr Microscopy and Magnetometry on Cr₂Ge₂Te₆ Exfoliated van-der-Waals Flakes |
| title_full_unstemmed | Wide-Field Kerr Microscopy and Magnetometry on Cr₂Ge₂Te₆ Exfoliated van-der-Waals Flakes |
| title_short | Wide-Field Kerr Microscopy and Magnetometry on Cr₂Ge₂Te₆ Exfoliated van-der-Waals Flakes |
| title_sort | wide field kerr microscopy and magnetometry on cr x2082 ge x2082 te x2086 exfoliated van der waals flakes |
| topic | Magnetic domains magnetic hysteresis magneto-optical Kerr microscopy MOKE magnetometry 2D magnetic materials van der Waals materials |
| url | https://ieeexplore.ieee.org/document/10771764/ |
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