Comparison of different approaches of wave vector resolved Brillouin light scattering spectroscopy for investigating interfacial Dzyaloshinskii–Moriya Interaction

In this thesis the effect of interfacial Dzyaloshinskii-Moriya-interaction (iDMI) is studied. This effect, which induces a frequency shift of spin waves with fixed wave vector, is investigated for different multilayers. Only spin waves with its wave vector perpendicular to the magnetization are detected. These spin waves are called surface waves. Brillouin light scattering (BLS) technique is used for the wave vector dependent detection of spin wave frequencies. Different setups were build and compared including a new setup, which does not use a focusing lens in front of the sample. This setup exhibits an increased wave vector resolution and simplifies changing between different samples. However, the signal intensity obtained by this setup is too low to measure spin waves under the given circumstances in reasonable time

Comparison of different approaches of wave vector resolved Brillouin light scattering spectroscopy for investigating interfacial Dzyaloshinskii–Moriya Interaction

In this thesis the effect of interfacial Dzyaloshinskii-Moriya-interaction (iDMI) is studied. This effect, which induces a frequency shift of spin waves with fixed wave vector, is investigated for different multilayers. Only spin waves with its wave vector perpendicular to the magnetization are detected. These spin waves are called surface waves. Brillouin light scattering (BLS) technique is used for the wave vector dependent detection of spin wave frequencies. Different setups were build and compared including a new setup, which does not use a focusing lens in front of the sample. This setup exhibits an increased wave vector resolution and simplifies changing between different samples. However, the signal intensity obtained by this setup is too low to measure spin waves under the given circumstances in reasonable time

Comparison of different approaches of wave vector resolved Brillouin light scattering spectroscopy for investigating interfacial Dzyaloshinskii–Moriya Interaction

In this thesis the effect of interfacial Dzyaloshinskii-Moriya-interaction (iDMI) is studied. This effect, which induces a frequency shift of spin waves with fixed wave vector, is investigated for different multilayers. Only spin waves with its wave vector perpendicular to the magnetization are detected. These spin waves are called surface waves. Brillouin light scattering (BLS) technique is used for the wave vector dependent detection of spin wave frequencies. Different setups were build and compared including a new setup, which does not use a focusing lens in front of the sample. This setup exhibits an increased wave vector resolution and simplifies changing between different samples. However, the signal intensity obtained by this setup is too low to measure spin waves under the given circumstances in reasonable time

Bipolar spin Hall nano-oscillators

We demonstrate a novel type of spin Hall nano-oscillators (SHNOs) that allow for efficient tuning of magnetic auto-oscillations over an extended range of gigahertz frequencies, using bipolar direct currents at constant magnetic elds. This is achieved by stacking two distinct magnetic materials with a platinum layer in between. In this device, the orientation of the spin polarised electrons accumulated at the top and bottom interfaces of platinum is switched upon changing the polarity of the direct current. As a result, the effective anti-damping required to drive large amplitude auto-oscillations can appear either at the top or bottom magnetic layer. Tuning of the auto-oscillation frequencies by several gigahertz can be obtained by combining two materials with sufficiently different saturation magnetization. Here we show that the combination of NiFe and CoFeB can result in 3 GHz shifts in the auto-oscillation frequencies. Bipolar SHNOs as such may bring enhanced synchronisation capabilities to neuromorphic applications