Role of manganese in ferromagnetic (Al,Mn)N films

We have studied the (Al,Mn)N films grown by plasma-enhanced molecular beam epitaxy via Raman spectroscopy to verify how Mn atoms were incorporated into AlN lattice. In Raman spectra of (Al,Mn)N, the frequency of E2 (high) mode blueshifts. Together with XRD results, the strain calculations support the existence of the substitutional dopant. Also, an additional peak, attributed to local vibrational mode of Mn, coincides with the calculated phonon frequency on the basis of a simple model. The Raman results reveal that Mn atoms replace Al atoms at the substitutional sites in the lattice. The (Al,Mn)N films were found to exhibit insulating characteristics and ferromagnetic ordering above room temperature. These results suggest that the ferromagnetism in the (Al,Mn)N films is due to the intrinsic nature originating from the substitutional Mn within (Al,Mn)N.