Spinformation : Domain walls, spin waves and entanglement

Abstract

This thesis uncovers new insights from research on the spinning electron that might lead to new information technologies. Magnetism plays a big role in computer devices, such as data storage, and is prospected to further push the boundaries of our computing capabilities. Furthermore, I pursue the development of quantum computing and sensing methods by exploring the entanglement in magnetic and elementary systems. We derive a theoretical model for the velocity of magnetic domain walls. By tuning parameters of that model we fit experimental observations and quantize the strength of the Dzyaloshinksii-Moriya-Interaction. The model describes the domain wall as a line that is pinned due to impurities, yet still able to creep due to thermal fluctuations. Moreover, we consider propagating perturbations of the spin orientation, i.e. spin waves, comparable to the "wave" in a soccer stadium. The wave itself moves around the tribune, but the soccer fans remain in their place. Sending information using this "wave" is much more efficient, moreover faster, than asking everyone to stand up and run around. In our research these spin waves are studied and employed in several systems and corresponding theoretical models. The quantum entanglement between the spin waves of an antiferromagnet are also investigated and might be exploited in quantum information applications such as quantum computers and the degree of entanglement can be a good indicator for transitions in the state of a material. Finally, I also study the entanglement on a more fundamental level, concerning two intervals of fermions with Lifshitz scaling symmetry.