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You searched for +publisher:"ETH Zürich" +contributor:("Acremann, Yves Marc"). Showing records 1 – 3 of 3 total matches.

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ETH Zürich

1. Dornes, Christian. Ultrafast studies on the coupling of magnetic and structural dynamics in solid-state ferromagnets.

Degree: 2018, ETH Zürich

The thesis describes primarily two experiments which investigate the coupling of structural and magnetic properties in solid-state ferromagnets on an ultrafast (\approx100~fs) timescale. To achieve this goal, both studies use ultrafast optical and x-ray pump-probe methods in combination, integrating information about magnetic and structural dynamics to form a more complete picture of the underlying physics. In the first experiment, the well-known shape-memory ferromagnetic Heusler alloy {Ni}2{MnGa} is studied. This compound is a multiferroic material stabilised by the correlations between electronic, magnetic, and structural order. The shape-memory effect is based on a structural phase transition between a low-temperature martensite phase and a high-temperature austenite phase. In both phases, the material is ferromagnetic. It has been observed for different stoichiometries that the martensite phase exhibits slightly incommensurate structural modulations whenever the shape-memory effect is present, but the exact connection between the two is unclear. We performed ultrafast optical measurements of the magnetisation of {Ni}2{MnGa}, using 100~fs, 800~nm pulses for both the pump and the magneto-optical Kerr effect probe. We found a rapid demagnetisation with a timescale of 320±50~fs, followed by a very slow recovery. At the FEMTO slicing source, we performed ultrafast x-ray diffraction on the weak (20201) satellite reflection of the (202) Bragg peak, which is a measure of the structural modulation. At high fluences of the 800~nm near-IR pump, we were able to observe a rapid and almost complete suppression of the structural modulation on a timescale of 300±40~fs, very similar to the behaviour of the magnetisation. However, the longer timescale dynamics are markedly different from the one observed in the magnetisation: we observed an intermediate recovery of the structural modulation, before a second drop was caused by the thermal phase transition to the high-temperature austenite structure, which does not support the structural modulation. Our conclusion is that magnetisation and structural modulation are not strongly coupled in {Ni}2{MnGa}, as the structural modulation was able to recover even while the material was demagnetised. The second experiment studied the movement of the lattice during ultrafast demagnetisation of a thin single-crystal iron film. While ultrafast demagnetisation is a very well-established effect, its microscopic mechanism remains unclear, especially with respect to the flow of angular momentum. Our goal was therefore to find a signature of the ultrafast Einstein – De Haas effect, i.e. the flow of spin angular momentum from the magnetisation to the mechanical angular momentum of the lattice. We identified that transverse shear waves would be launched from the surfaces of a rapidly demagnetising crystal, with an initial deflection whose direction depends on the magnetisation. A double-grazing x-ray diffraction geometry to measure the crystal… Advisors/Committee Members: Johnson, Steven, id_orcid0000-0001-6074-4894, Acremann, Yves Marc, id_orcid0000-0002-4109-3544, Pontius, Niko.

Subjects/Keywords: Ultrafast optics; Ultrafast magnetization dynamics; X-ray diffraction; Multiferroics; Iron; Ultrafast demagnetization; Angular momentum; info:eu-repo/classification/ddc/530; info:eu-repo/classification/ddc/530; Physics; Physics

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APA (6th Edition):

Dornes, C. (2018). Ultrafast studies on the coupling of magnetic and structural dynamics in solid-state ferromagnets. (Doctoral Dissertation). ETH Zürich. Retrieved from http://hdl.handle.net/20.500.11850/331285

Chicago Manual of Style (16th Edition):

Dornes, Christian. “Ultrafast studies on the coupling of magnetic and structural dynamics in solid-state ferromagnets.” 2018. Doctoral Dissertation, ETH Zürich. Accessed April 17, 2021. http://hdl.handle.net/20.500.11850/331285.

MLA Handbook (7th Edition):

Dornes, Christian. “Ultrafast studies on the coupling of magnetic and structural dynamics in solid-state ferromagnets.” 2018. Web. 17 Apr 2021.

Vancouver:

Dornes C. Ultrafast studies on the coupling of magnetic and structural dynamics in solid-state ferromagnets. [Internet] [Doctoral dissertation]. ETH Zürich; 2018. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/20.500.11850/331285.

Council of Science Editors:

Dornes C. Ultrafast studies on the coupling of magnetic and structural dynamics in solid-state ferromagnets. [Doctoral Dissertation]. ETH Zürich; 2018. Available from: http://hdl.handle.net/20.500.11850/331285

2. Gort, Rafael. Ultrafast spin dynamics in 3d transition metals.

Degree: 2018, ETH Zürich

Subjects/Keywords: info:eu-repo/classification/ddc/530; Physics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Gort, R. (2018). Ultrafast spin dynamics in 3d transition metals. (Doctoral Dissertation). ETH Zürich. Retrieved from http://hdl.handle.net/20.500.11850/315036

Chicago Manual of Style (16th Edition):

Gort, Rafael. “Ultrafast spin dynamics in 3d transition metals.” 2018. Doctoral Dissertation, ETH Zürich. Accessed April 17, 2021. http://hdl.handle.net/20.500.11850/315036.

MLA Handbook (7th Edition):

Gort, Rafael. “Ultrafast spin dynamics in 3d transition metals.” 2018. Web. 17 Apr 2021.

Vancouver:

Gort R. Ultrafast spin dynamics in 3d transition metals. [Internet] [Doctoral dissertation]. ETH Zürich; 2018. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/20.500.11850/315036.

Council of Science Editors:

Gort R. Ultrafast spin dynamics in 3d transition metals. [Doctoral Dissertation]. ETH Zürich; 2018. Available from: http://hdl.handle.net/20.500.11850/315036


ETH Zürich

3. Salvatella Orgillés, Gerard. Experiments on femtomagnetism.

Degree: 2016, ETH Zürich

Subjects/Keywords: LASER PULSES/FEMTOSECOND PHENOMENA (LASER ENGINEERING); MAGNETISIERUNGSVORGÄNGE (ELEKTROMAGNETISMUS); FERROMAGNETISMUS; FERROMAGNETISM; LASERPULS/FEMTOSEKUNDEN-PHÄNOMENE (LASERTECHNIK); MAGNETOOPTIK (MAGNETISMUS); MAGNETIZATION PROCESSES (ELECTROMAGNETISM); MAGNETOOPTICS (MAGNETISM); info:eu-repo/classification/ddc/530; Physics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Salvatella Orgillés, G. (2016). Experiments on femtomagnetism. (Doctoral Dissertation). ETH Zürich. Retrieved from http://hdl.handle.net/20.500.11850/125707

Chicago Manual of Style (16th Edition):

Salvatella Orgillés, Gerard. “Experiments on femtomagnetism.” 2016. Doctoral Dissertation, ETH Zürich. Accessed April 17, 2021. http://hdl.handle.net/20.500.11850/125707.

MLA Handbook (7th Edition):

Salvatella Orgillés, Gerard. “Experiments on femtomagnetism.” 2016. Web. 17 Apr 2021.

Vancouver:

Salvatella Orgillés G. Experiments on femtomagnetism. [Internet] [Doctoral dissertation]. ETH Zürich; 2016. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/20.500.11850/125707.

Council of Science Editors:

Salvatella Orgillés G. Experiments on femtomagnetism. [Doctoral Dissertation]. ETH Zürich; 2016. Available from: http://hdl.handle.net/20.500.11850/125707

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