Thema der Dissertation:
Ultraschnelle Magnetisierungsdynamik ferromagnetischer Schichtsysteme
Ultraschnelle Magnetisierungsdynamik ferromagnetischer Schichtsysteme
Abstract: This work is concerned with the ultrafast magnetization dynamics found in rareearth and transition metals. In the first part, we have investigated the magnetization dynamics of 60 nm Gd(0001) grown on W(110) in XMCD in reflection. Our analysis shows that the ultrafast timescale of demagnetization, which was found by previous authors in 10 nm thick Gd films can be attributed to effects at the Gd/W interface, which we interpret as magnon driven spin currents.
In the second part of the work, we have applied both XRMR and XMCD in reflection to study the magnetic structure of synthetic ferrimagnet Fe/Gd grown on W(110). We find clear signs of a twisted magnetization state, as proposed by Camley and Tilley in which both layers form a domain-wall-like structure with the magnetic moments being aligned almost perpendicular to the field at the Fe/Gd interface and tilting stepwise towards field-aligned throughout both layers.
We further find very diverse magnetization dynamics in XMCD in reflection, ranging from an increase of the detected magnetization component on a slow ps-timescale to all-optical switching of only the Gd component within less than 1 ps. The differences are caused by the temperature dependent orientation of the magnetization in the twisted state. As it can likewise be manipulated by the external magnetic field strength, synthetic ferrimagnets offer a great amount of controllability of their magnetization dynamics.
In the second part of the work, we have applied both XRMR and XMCD in reflection to study the magnetic structure of synthetic ferrimagnet Fe/Gd grown on W(110). We find clear signs of a twisted magnetization state, as proposed by Camley and Tilley in which both layers form a domain-wall-like structure with the magnetic moments being aligned almost perpendicular to the field at the Fe/Gd interface and tilting stepwise towards field-aligned throughout both layers.
We further find very diverse magnetization dynamics in XMCD in reflection, ranging from an increase of the detected magnetization component on a slow ps-timescale to all-optical switching of only the Gd component within less than 1 ps. The differences are caused by the temperature dependent orientation of the magnetization in the twisted state. As it can likewise be manipulated by the external magnetic field strength, synthetic ferrimagnets offer a great amount of controllability of their magnetization dynamics.
Time & Location
Oct 11, 2024 | 02:00 PM
Hörsaal A (1.3.14)
Fachbereich Physik, Arnimallee 14, 14195 Berlin