Elastically strained and relaxed La0.67Ca0.33MnO3 films grown on lanthanum aluminate substrates with different orientations

Resumo

Structure of 40-nm thick La_0.67Ca_0.33MnO₃ (LCMO) films grown by laser evaporation on (001) and (110) LaAlO₃ (LAO) substrates has been investigated using the methods of medium-energy ion scattering and X-ray diffraction. The grown manganite layers are under lateral biaxial compressive mechanical stresses. When (110)LAO wafers are used as the substrates, stresses relax to a great extent; the relaxation is accompanied by the formation of defects in a (3–4)-nm thick manganite-film interlayer adjacent to the LCMO–(110)LAO interface. When studying the structure of the grown layers, their electro- and magnetotransport parameters have been measured. The electroresistance of the LCMO films grown on the substrates of both types reached a maximum at temperature T_M of about 250 K. At temperatures close to T_M magnetoresistance of the LCMO/(110)LAO films exceeds that of the LCMO/(001)LAO films by 20–30%; however, the situation is inverse at low temperatures (T < 150 K). At T < T_M, the magnetotransport in the grown manganite films significantly depends on the spin ordering in ferromagnetic domains, which increase with a decrease in temperature.