there really is no such thing as matrix division.
matlab lets you do it and understands that you are using it as a convoluted way to write ax=b (rewritten improperly as x = b/a or b\a or whatever it is, my matlab is a few years behind me)
so in eigen you need to either do the underlying math by hand or use a solver depending on what you think division means. If you think a*b = c, then it may involve an inverse or pseudoinverse.
if you want the solution to a system, then you need to use whatever they provide for that.