Electronic structure and spontaneous magnetization in Mn-doped SnO2

Abstract

Mn-doped SnO2 is a promising dilute magnetic semiconductor; however, there are many inconsistent reports on the magnetic ordering in the literature. We investigate the magnetic ordering and the local electronic structure in stoichiometric and Mn-doped (with Mn concentrations of 1 at.%, 3 at.%, and 6 at.%) SnO2 using magnetization measurements, Mn L2,3-edge and O K-edge x-ray absorption fine structure measurements, and density functional theory and model Hamiltonian calculations. We find that paramagnetic and ferromagnetic behavior is present as a function of Mn concentration and, in particular, that paramagnetic, ferromagnetic, and antiferromagnetic order coexist independently in Mn(6%):SnO2. Simultaneously, we find that Mn2+, Mn3+, and Mn4+ also coexist in Mn(6%):SnO2. These findings demonstrate the care needed to study Mn:SnO2 and point to the wealth of magnetic behaviors that might be realized with careful control of synthesis conditions.