Inhaltszusammenfassung

The work which has been conducted in the course of this doctoral thesis with the title “Cavity Magnon Polariton Spectroscopy” can be classified as part of the recent and active research area of cavity spintronics. Among others, cavity spintronics aims to study light-matter interaction by the examination of the properties of the cavity-magnon polariton (CMP) and harness the CMP for applications bridging concepts of cavity quantum electrodynamics (CQED) with spintronics. The CMP is the ass...The work which has been conducted in the course of this doctoral thesis with the title “Cavity Magnon Polariton Spectroscopy” can be classified as part of the recent and active research area of cavity spintronics. Among others, cavity spintronics aims to study light-matter interaction by the examination of the properties of the cavity-magnon polariton (CMP) and harness the CMP for applications bridging concepts of cavity quantum electrodynamics (CQED) with spintronics. The CMP is the associated quasiparticle resulting from the hybridisation of strongly coupled cavity photon-magnon (quasiparticles from a collective spin excitation in a magnetic material) states. In close collaboration with co-workers from the Karlsruhe Institute for Technology (KIT) who provided for the millikelvin data at 30 mK, the work on the CMP started with conducting a study on the temperature dependence of key properties of the CMP such as the cooperativity C, that is, the coupling strength and the magnon linewidth from 30mK to 290 K. This work connects the quantum regime at millikelvin temperatures with the classical regime at room temperature and shows the persistence of the strong coupling regime, that is the existence of a coherent exchange of information, as C > 1 for the entire temperature range. However, beyond the realisation of strong coupling, real applications using CMPs require the ability to tune and control of the key property, i.e. the coupling strength reliably and reproducibly. For instance, it is necessary to switch the coherent exchange of information on and off deliberately. Therefore, as the next step, a new experimental scheme allowing such control over the coupling strength has been developed in the course of this thesis. Instead of the generally used approach of a single-tone driven CMP in the field of cavity spintronics, an approach driving the CMP with two tones is realised. The coupling strength is controlled by the relative phase and amplitude between the intracavity fields from the two inputs. It is shown that the coupling strength can be increased, decreased to zero accompanied by a strong amplitude enhancement and the decrease of the signal’s linewidth, or transferred to a regime of level merging where the coupling strength is a complex quantity. Also, that method does not require any intrusion into the experimental apparatus during measurements. Thus, by the combination of realising strong coupling and the control of the coupling of the CMP, this work contributes to cavity spintronics. Specifically, the control over the coupling strength opens an avenue for generalized control of the coupling of other solid-state polaritons towards the development of applications for data storage and information processing technologies.» weiterlesen» einklappen

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DDC Sachgruppe:
Physik