I am a PhD student in my second year, and I am thinking about doing a doctoral stay in some foreign university with a group that works on the same topic as I am. I do know about some interesting research groups where I could do this kind of doctoral activity. However, I am unsure about how does some proceed to pursue this kind of research position.
Does one directly write to the group presenting yourself and what are you doing (also presenting some of your published work)? Do you have to follow a formal application at the target university? Does it depend on the country/institution?