Studium spintronických jevů v magneticky uspořádaných strukturách pomocí terahertzové spektroskopie

Kubaščík, Peter

The main objective of this thesis was to bring the first experimental evidence about the spin-Hall magnetoresistance (SMR) in the Terahertz (THz) spectral range. The time-domain THz spectroscopy (TDTS) was chosen as the main method, and we presented a new experimental scheme, which allows us to observe SMR or magnetoresistive effects with similar symmetry at a wide range of THz frequencies very efficiently. We focused on the study of SMR in the bilayers consisting of either a prototypical ferrimagnetic isolator or of heavy metal (FI/HM) and metallic stacks of ferromagnetic CoFeB and heavy metal Pt layer (FM/HM). While SMR shows a rapid decrease already at the lowest THz frequencies (< 1 THz) in the FI/HM structures, the SMR in FM/HM bilayers persists above 30 THz. These observations are then explained by a different mechanism of SMR. The second part of the thesis is devoted to the construction of the new TDTS setup and an easy-to-use model of the THz setup using the Gaussian description of THz radiation. The simulated results have been compared to corresponding experimental measurements using a spintronic THz emitter (STE). The last part of the thesis describes the emission of intensive THz pulses from large-area STE.

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