Magnetic semiconductor materials are best known for their spin-filtering properties which can effectively create highly polarized spin currents from nonmagnetic electrodes. One can readily generate and analyze spin information through quantum tunneling across these materials. Magnetic semiconductors have another less explored property: interfacial exchange fields onto neighboring electronic systems. Through indirect exchange interaction between the localized magnetic moments and the adjacent free electrons, the electron spins experience an effective Zeeman field on the order of tens of Tesla. This effect is especially pronounced on low-dimensional systems such as 2DEG and topological materials. We first probe its strength on a cluster of Al nano dots under Coulomb confinement, then proceed to show a number of material and device concepts for spintronic and quantum information applications originating from such spin filtering and interfacial exchange effects.