Discrete deposition as a powerful tool to govern magnetoresistance of the doped manganite films

Abstract

A peculiar preparation routine, namely, a discrete deposition, is proposed for a goal-oriented change of electric and magnetotransport properties of the doped manganite films. The distinguishing feature of such procedure is a division of the whole deposition process into several cycles consisting of the deposition itself and subsequent annealing of the sample in the deposition chamber. The investigations were carried out on a series of (La,Sr)MnO3 films with different numbers of deposition cycle n (1⩽n⩽5), as well as on a single-layer reference film. All the films were deposited on single-crystalline SrTiO3 (001) substrates held at a temperature of 700°C in Ar–O2 mixture using reactive magnetron sputtering technique and subjected to a postdeposition annealing at 750°C. It has been shown that the discrete deposition procedure results in the increase of the magnetic transition temperature, substantial drop of the resistivity, and reduction of the extrinsic magnetoresistance. It is shown that the proposed procedure strongly affects the dynamics of the film growth, minimizes the effects caused by substrate-induced stress, and leads to the improvement of the structural and magnetic homogeneities of the film layers, which are not adjacent to the substrate. All these effects become especially efficient for n⩾2.