Microwave Absorption Studies on the Frustrated Kitaev Model Candidate Material alpha-RuCl3

Master's Thesis from the year 2018 in the subject Physics - Experimental Physics, grade: 1,0, Dresden Technical University (IFW Dresden), language: English, abstract: This study is dedicated to the examination of the low-energy (< 1000 GHz) exci-tations of ¿-RuCl3 at the ¿-point of the momentum space (q = 0), probed by field-dependent microwave (MW) absorption. The first goal is to verify statements and values already determined in other works and with other methods to ensure the validity of the conjectures made of our own data. The second goal is to extend the present state of the art by the information gained by MW absorption and give a plausible interpretation of the observations, which includes finding an appropriate model for the system. Thirdly, a general understanding of microwave absorption, in particular of the resonant case, and of frustrated systems (as being an important general topic) should have been developed during the course of this work.

After developing some theoretical background necessary for the interpretation of the ensuing data (chapter 1), which encompasses frustration, the Kitaev model, magnetic moments, spin Hamiltonians and a description of the experimental methods (microwave absorption, in particular electron spin resonance, and magnetometry), the experimental setups are shown to get some practical insights in the methods which were used (chapter 2). In chapter 3, the magnetization data as well as the data of microwave absorption, which constitutes the central part of this work, are shown and thoroughly discussed. Finally, in chapter 4, a summary together with concluding remarks are given, and a first glance of possible continuation of this project is presented.