Quantum-size effect and tunneling magnetoresistance in   ferromagnetic-semiconductor quantum heterostructures
  We report on the resonant tunneling effect and the increase of tunneling magnetoresistance (TMR) induced by it in ferromagnetic-semiconductor GaMnAs quantum-well heterostructures. The observed quantum levels of the GaMnAs quantum well were successfully explained by the valence-band kp model with the p-d exchange interaction. It was also found that the Fermi level of the electrode injecting carriers is important to observe resonant tunneling in this system. 
S. Ohya, P. N. Hai, Y. Mizuno, and M. Tanaka