Samathrakis, Ilias (2022)
Topological transport properties of ferromagnetic and antiferromagnetic materials.
Technische Universität Darmstadt
doi: 10.26083/tuprints-00022914
Dissertation, Erstveröffentlichung, Verlagsversion
Kurzbeschreibung (Abstract)
Magnetic materials are of fundamental importance to the welfare of our society since they find use, among others, in energy harvesting applications. The rapid technological development requires the generation of new environment friendly methods to power up novel devices, therefore, thermoelectric materials become vital for future applications. A particular class of magnetic materials that can be used in thermoelectric devices is those with nontrivial band topology, such as Weyl and nodal line semimetals, that have recently attracted intensive attention due to their interesting properties.
The anomalous Hall (Nernst) effect, being the generation of a transverse spin polarized charge current as a response to a longitudinal charge current (thermal gradient), was initially associated to ferromagnets. Recently however, it was demonstrated that collinear and non-collinear antiferromagnets can induce finite values, making them interesting for novel applications. These findings though, not only challenged the current understanding of the theoretical background but also the conditions of their existence, being till nowadays pending problems.
In this work, a computational framework to construct maximally localized Wannier functions in an automatic way is provided and subsequently used to calculate the anomalous Hall and Nernst conductivities of ferromagnetic and non-collinear antiferromagnetic intermetallic compounds, with a high success rate of 92%. Detailed symmetry analysis is performed in order to reveal the vanishing anomalous Hall and Nernst conditions in certain ferromagnetic and antiferromagnetic compounds. It is demonstrated that the large values of anomalous Hall and Nernst conductivities are due to the presence of Weyl nodes, nodal lines and small gap areas and that they can further be tuned by means of external stimuli, leading to further enhancement of the anomalous Hall and Nernst conductivities.
In the future, the automated Wannier function workflow can be used to construct the maximally localized Wannier functions of any 3d transition-metal based system, with or without the inclusion of spin-orbit interaction with minimum human intervention and external stimuli can be used to further enhance the topological transport properties of a compound.
| Typ des Eintrags: | Dissertation | ||||
|---|---|---|---|---|---|
| Erschienen: | 2022 | ||||
| Autor(en): | Samathrakis, Ilias | ||||
| Art des Eintrags: | Erstveröffentlichung | ||||
| Titel: | Topological transport properties of ferromagnetic and antiferromagnetic materials | ||||
| Sprache: | Englisch | ||||
| Referenten: | Zhang, Prof. Hongbin ; Mokrousov, Prof. Yuriy | ||||
| Publikationsjahr: | 2022 | ||||
| Ort: | Darmstadt | ||||
| Kollation: | xi, 129 Seiten | ||||
| Datum der mündlichen Prüfung: | 4 November 2022 | ||||
| DOI: | 10.26083/tuprints-00022914 | ||||
| URL / URN: | https://tuprints.ulb.tu-darmstadt.de/22914 | ||||
| Kurzbeschreibung (Abstract): | Magnetic materials are of fundamental importance to the welfare of our society since they find use, among others, in energy harvesting applications. The rapid technological development requires the generation of new environment friendly methods to power up novel devices, therefore, thermoelectric materials become vital for future applications. A particular class of magnetic materials that can be used in thermoelectric devices is those with nontrivial band topology, such as Weyl and nodal line semimetals, that have recently attracted intensive attention due to their interesting properties. The anomalous Hall (Nernst) effect, being the generation of a transverse spin polarized charge current as a response to a longitudinal charge current (thermal gradient), was initially associated to ferromagnets. Recently however, it was demonstrated that collinear and non-collinear antiferromagnets can induce finite values, making them interesting for novel applications. These findings though, not only challenged the current understanding of the theoretical background but also the conditions of their existence, being till nowadays pending problems. In this work, a computational framework to construct maximally localized Wannier functions in an automatic way is provided and subsequently used to calculate the anomalous Hall and Nernst conductivities of ferromagnetic and non-collinear antiferromagnetic intermetallic compounds, with a high success rate of 92%. Detailed symmetry analysis is performed in order to reveal the vanishing anomalous Hall and Nernst conditions in certain ferromagnetic and antiferromagnetic compounds. It is demonstrated that the large values of anomalous Hall and Nernst conductivities are due to the presence of Weyl nodes, nodal lines and small gap areas and that they can further be tuned by means of external stimuli, leading to further enhancement of the anomalous Hall and Nernst conductivities. In the future, the automated Wannier function workflow can be used to construct the maximally localized Wannier functions of any 3d transition-metal based system, with or without the inclusion of spin-orbit interaction with minimum human intervention and external stimuli can be used to further enhance the topological transport properties of a compound. |
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| Alternatives oder übersetztes Abstract: |
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| Freie Schlagworte: | DFG|SPP1666|Topological Insulators: Materials - Fundamental Properties - Devices | ||||
| Status: | Verlagsversion | ||||
| URN: | urn:nbn:de:tuda-tuprints-229142 | ||||
| Sachgruppe der Dewey Dezimalklassifikatin (DDC): | 500 Naturwissenschaften und Mathematik > 500 Naturwissenschaften 500 Naturwissenschaften und Mathematik > 530 Physik |
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| Fachbereich(e)/-gebiet(e): | 11 Fachbereich Material- und Geowissenschaften 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Theorie magnetischer Materialien |
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| Hinterlegungsdatum: | 28 Nov 2022 13:41 | ||||
| Letzte Änderung: | 29 Nov 2022 06:27 | ||||
| PPN: | |||||
| Referenten: | Zhang, Prof. Hongbin ; Mokrousov, Prof. Yuriy | ||||
| Datum der mündlichen Prüfung / Verteidigung / mdl. Prüfung: | 4 November 2022 | ||||
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