c-Axis epitaxial thin films of a layered manganate La 2À2x Sr 1þ2x Mn 2 O 7 have been grown on SrTiO 3 (100) substrates by on-axis rf-magnetron sputtering. The films have been characterized using energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), high resolution scanning electron microscopy (HRSEM), magnetoresistivity, and magnetization measurements. It is shown that the film chemical composition is sensitive to the deposition parameters, and that a small deviation of composition or deposition condition causes nucleation of the (La,Sr)MnO 3 structure. It is found that the deposition rate is crucial for the c-axis film growth; stoichiometric c-axis La 2À2x Sr 1þ2x Mn 2 O 7 films have been grown under limited conditions of a low rate of 0.8 nm/min, an (Ar, O 2 50%) atmospheric pressure of 120 mTorr, and a substrate temperature of 760 C. From X-ray diffraction simulation, it is inferred that the c-axis La 2À2x Sr 1þ2x Mn 2 O 7 films thus grown contain intergrowths comprised of (La,Sr)MnO 3 and presumably (La,Sr) 2 MnO 4 structures, and the total intergrowth fraction amounts to about 40%.

c-Axis epitaxial thin films of the bilayer manganates La 2À2x Sr 1þ2x Mn 2 O 7 (LSMO327) and La 2À2x Sr 1þ2x Mn 2Ày Cu y O 7 (x ¼ 0:3, y ¼ 0:2) (LSMCO327) have been fabricated. It is found that Cu-substitution is effective in improving the c-axis epitaxy, which is difficult to attain in this layered system.

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