Improvement in spin-wave resonance characteristics of epitaxial barium-ferrite thin films by using an aluminum-doped strontium-ferrite buffer layer

We report on the effects of using SrFe7Al5O19 as a buffer layer for growth of high-quality epitaxial barium-ferrite thin films on sapphire substrates. X-ray diffraction studies reveal that the buffer layer causes the interfac ial strains in the barium-ferrite films to relax. As a result, the ferromag netic resonance linewidth decreases even in the as-deposited case. However. the more striking result is the drastic reduction in the linewidth that oc curs when the barium-ferrite film is deposited on the buffer layer and subs equently annealed at 1000 degrees C for 2 h, allowing the observation of a large number of spin-wave resonances (up to the 15th mode), indicating an i mprovement in both thr surface and interface characteristics. (C) 1999 Amer ican Institute of Physics. [S0003-6951(99)02604-2].