Spin Dynamics in Ordered Magnetic Systems
Date
2018-05
Authors
Islam, Farhan
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Abstract
Ordered systems such as crystals possess collective excitations also associated with thermal vibrations. These collective vibrations have been found to have wavelengths that are correlated with their energies. Similarly, ordered magnetic systems, such as the one in figure 1(a), also exhibit excitations that are known as spin-waves, as shown in figure 1(b), and they also show strong dependence between their energy and their wavelengths. The dependence for the particular ground state in figure 1(a) is shown in figure 1(c). In this project, we determine the energy scale associated with the interaction between nearest-neighbor spins and also next-nearest neighbor spins in two dimensions for both ferromagnetic and anti-ferromagnetic ordering of spins in the ground state. We can then use this theoretical prediction and experimentally observed dispersion relation, using neutron scattering, to model the system and extract interaction properties between spins. This information is very useful in designing materials and understanding their magnetic and electronic properties.
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