To take part in the PCD network's Mobility Program, M.A. and PhD students require an informal letter from a mentor offering to supervise their research during their stay at Freie Universitaet Berlin. A mentor should be a humanities professor at the FUB whom you choose and contact on your own before your stay. An overview of those teaching in the humanities at Freie Universitaet Berlin can be found here.
A mentor must not necessarily be a professor working in your own field. Nonetheless, you will be affiliated with the institute of your mentor during your stay.
PostDocs are asked to show that they have already established contact with researchers at Freie Universitaet Berlin (e.g., with an extract from an email).