Hi.
I'm new here and have been working (rather thinking) about the idea you are about to see for years. It's a rather practical idea but I believe it might as well be very effective.
It revolves around nickel or gadolinium and the curie temperature and switching magnetic field of >arbitrary< strength without using (more) power, which could very possibly result in more energy output than energy used to for switching the magnetic field.
I'm not really good at explaining it in written language so I made two CGI videos using Blender about it a while back. They are pretty self explanatory and frankly the idea is rather simple and practical.
Please take a look at it and tell me what you think about it.
This is the last video I made and I consider it the final design: https://www.youtube.com/watch?v=s2MjVcirx0Q
However, I made a video last year to just illustrate the idea of switching magnetic fields with gadolinium or nickel. The idea was not mature at that time, but that video might also be useful to clear some things up (the main principle, rather than a possibly working concept). There are some flaws and mistakes in this video but it might aid better comprehension. here it is: https://www.youtube.com/watch?v=lkJq40qPcGg
Thank you for your time. looking forward to see what you think about it.