# Magnon Bose Einstein Kondensation for Non Physicists

The intent of this document is to introduce non-specialists, especially students but also researchers that are new to the field and would like to read a comprehensive introduction, to the very complex issue of magnon-Bose-Einstein-condensation (mBEC). Magnon Bose-Einstein condensation is a phenomenon that has been discovered in 2006 by our work group. It is a very interesting phenomenon which arises from thermodynamics and quantum mechanics.

Both subjects are complex physical theories. In the following pages I will try to describe these phenomena with as little mathematics as possible. Nevertheless it is sometimes inevitable to introduce a formula as it is the most elegant way to describe physical dependencies. I will try to keep the mathematic formulas on a level that should be accessible to most high-school graduates.

In general, new physical concepts build up on old ones. As the topic of mBEC is a rather new discovery, a lot of background knowledge is required to understand it. For this purpose more than half of the document deals with physical concepts that are needed to understand mBEC. Unfortunately these concepts build on more elementary concepts on their own. It lies outside the scope of this document to go down to elementary physical concepts, as this would reach the volume of a whole encyclopedia. Instead I will use Wikipedia links to elementary physical concepts wherever needed.

Wikipedia is a free encyclopedia to which everyone can contribute. This of course bears the risk that some of the linked Wikipedia articles might be temporarily incorrect if a non specialist edits one of them. My impression is that nearly all Wikipedia articles about physics are written by specialists (physicists or engineers) and are therefore correct. These Articles are also monitored by the authors, so that every wrong edit is generally removed within one day.

If you have strong doubts about the correctness of a linked article please contact me and I will try to correct it if it is really incorrect. If it is correct but formulated in a way that makes it difficult to understand I will expand the article to make it clearer.

The first section deals with the question: What is condensation?

Patryk Nowik-Boltyk, 6th June 2012

Institut für Angewandte Physik
AG Demokritov/Nichtlineare Magnetische Dynamik

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