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Disputation Seyed Mohammadreza Rouzegar

18.04.2024 | 16:00
Thema der Dissertation:
Laser-driven terahertz spin transport: driving force and applications
Abstract: The field of spin-based electronics (spintronics) emerges as a promising solution to the challenges encountered in charge-based electronics by using the spin-degree of freedom. In order to make spintronic operations compatible and competitive with other information carriers, such as electrons in field-effect transistors and photons in optical fibers, it is essential to push their speed to femtosecond time scale and, thus, into the terahertz (THz) frequency range.
This thesis focuses on the investigating spin transport at THz frequencies, particularly exploring THz spin transport in F|N heterostructures, where F represents a metallic ferromagnet such as iron (Fe) and N denotes a non-magnetic metal like platinum (Pt). Upon exciting the F|N sample with an ultrashort laser pulse, a spin current is induced from the ferromagnetic layer into the non-magnetic layer. This work adresses fundamental questions such as: what is the primary driving force for the spin current?
In the subsequent step, spin propagation through a nonmagnetic intermediate layer X is studied. We consider two extreme choices of X: a highly conductive metal X=Cu and insulating X=MgO. Spin transport through Cu and MgO covers an entirely different modes of spin propagation, band-like electron transport and tunneling, respectively.
Finally, we turn to applications by building upon the insights gained in this thesis. Specifically, we improve the performance of spintronic terahertz emitters to generate THz electric fields with amplitude as high as 1.5 MV/cm and full width at maximum of approximately 100 fs.

Zeit & Ort

18.04.2024 | 16:00

Seminarraum T2 (1.4.03)
(Fachbereich Physik, Arnimallee 14, 14195 Berlin)