Characterization of ferromagnetic and antiferromagnetic systems using nitrogen-vacancy center relaxometry
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Date
2024
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Abstract
Relaxometry with nitrogen-vacancy (NV) centers in diamond is an innovative and non-invasive technique that has been increasingly used for characterizing magnetic materials. Because of their exceptional quantum coherence and capability to be manipulated optically, it is possible to measure their relaxation time and, from this quantity, probe physical characteristics of the environment. This technique is the so-called called relaxometry. During the last few years, NV centers have been used for measuring magnetic properties in ferromagnetic materials, and a few times for antiferromagnetic systems with easy-axis anisotropy.In this work, we develop a complete theoretical description of NV center relaxometry for several types of magnetic materials (ferromagnetic and antiferromagnetic systems), we indicate what physical parameters can be measured in each situation, when this technique will experimentally work, and how it depends on the sample anisotropy. We found that relaxation rates using ferromagnetic systems peak at certain values of the external magnetic field, where both NV center and sample resonate simultaneously, something that does not happen when using antiferromagnets because of their high resonance frequency. In this way, NV center relaxometry allows us to extract information about the spin waves of the system. Finally, we discuss prospects to non-intrusively probe magnetic properties and phase transitions in ferrimagnetic systems, in triangular-lattice antiferromagnets, such as Cs2CuCl4 and in 2D materials.
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Tesis (Master’s Degree in Physics)--Pontificia Universidad Católica de Chile, 2024.