I'd like to to establish and detect Hall current in other than group 3a compounds ... anyone here experimented with that and willing to share their findings?

I don't work in this area, but the Hall effect has been demonstrated in a lot more than just group 3a elements. For example, silicates of transition metals can have very interesting Hall properties. Here is a link to nice paper in Nature Materials from last year: http://www.phys.lsu.edu/dept/direct/largeanomalous.pdf