Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 20: Focus Session: Magnetic Semiconductors (jointly with MA)

HL 20.5: Talk

Monday, March 26, 2012, 17:30–17:45, EW 202

Influence of the interface structure on the magnetic proximity polarization in Fe/(Ga,Mn)As bilayers — •S. Polesya¹, S. Mankovsky¹, J. Minar¹, H. Ebert¹, M. Sperl², and C. Back² — ¹Universität München, Department Chemie, Butenandtstr. 5-13, D-81377 München, Germany — ²Institut für Experimentelle Physik, Univ. Regensburg, Germany

We present the results of detailed investigations on the influence of various conditions at the interface on the magnetic proximity polarization effect for the Fe/(Ga_0.95Mn_0.05)As system. The ab initio electronic structure calculations were performed using the TB-KKR Green’s function method. These allow the calculation of the exchange coupling parameters between magnetic atoms in the system. The finite temperature magnetic properties were determined then by means of Monte Carlo simulations. The exchange coupling between Fe and Mn atoms in the vicinity of the Fe/(Ga,Mn)As interface is found to be strongly dependent on the Mn atom position in the lattice. In particular, the substitutional Mn is coupled antiferromagnetically to Fe for Ga- as well as As-terminated interfaces while the Mn at the interstitial positions is coupled ferromagnetically to Fe. As a result, the total magnetization of the (Ga,Mn)As film can be aligned ferromagnetically with Fe. This effect is larger for As-termination. In addition, presence of the Mn interstitials influences the interaction between substitutional Mn. It is shown that a complicated competition of FM and AFM interactions between Mn atoms results in a disordered magnetic structure close to the interface with Fe.