Influence of the substrate on growth and magnetoresistance of La0.7Ca0.3MnOz thin films deposited by magnetron sputtering

Abstract

Off-axis radio frequency magnetron sputtering was employed to grow La0.7Ca0.3MnOz (LCMO) thin films onto three different types of substrates. The substrate strongly influences the structure and the colossal magnetoresistance effect of the obtained films. Single-crystalline thin films were prepared on LaAlO3 (100) substrates, showing a low value of residual resistivity and a metal–insulator transition at a temperature of up to Tpeak=290 K. The latter value of the transition temperature is one of the highest reported so far on thin films of the La–Ca–Mn–O system. Films deposited onto Y-stabilized ZrO2 substrates and onto MgO substrates are polycrystalline and less textured. These films are characterized by a large negative magnetoresistance ratio MR=[R(H)−R(0)]/R(0) measured for small values of the magnetic field H. For H=1.5 kOe, the MR was found to be approximately −30%, −20%, and −8% at temperatures of 20, 77, and 180 K, respectively. The magnetoresistance of polycrystalline LCMO films shows two contributions, a low-field MR and a high-field MR, which are different in their dependence on temperature. The low-field MR is related to the magnetization process and can be attributed to scattering processes in domain walls or to tunneling of polarized charge carriers between the grains of the polycrystalline films.

Detailed magnetic and structural properties of exchange‐biased La1‐xCaxMnO3

“…We determined the c-axis lattice parameter for F and AF films at 0.385 ± 0.002 nm and 0.376 ± 0.002 nm, respectively [15]. Our results revealed that the F film agrees well with the bulk value obtained for this type of manganite (0.3867 nm) [16], whereas the AF film exhibits a larger deviation with respect to other reports (0.381 nm). Similarly, the substrate lattice parameter was estimated from the (00l) Bragg-Peak position observed, obtaining approximately 0.389±0.002 nm for SrTiO 3 , which is consistent with the expected substrate lattice parameter of 0.390 nm [17].…”

Structural, Magnetic and Transport Properties οf NdBaCo2O5+xThin Films Deposited by Magnetron Sputtering

“…The deposition procedure used for NdBaCo 2 O 5+x films was close to that developed for the epitaxial growth of La 0.7 Ca 0.3 MnO 3 and La 0.7 Sr 0.3 MnO 3 thin films [11,12]. The chamber pressure was the same p = 10 Pa, while the substrate temperature T sub was modified over the range from 580…”

Low-Field Magnetoresistance in Manganite Thin Films

“…It was shown in our previous work [5,6] that the deposition temperature and mismatch of the lattice constants between the manganite film and the substrate have a crucial influence on the film growth. For a very low lattice mismatch the obtained films are single crystalline independent of employed deposition technique.…”

“…Recently the colossal magnetoresistance (CMR) phenomenon has attracted much attention as both a fundamental research and an applied science challenge [1]. It has been demonstrated that low-field magnetoresistance (LFMR) effects have an important influence in bulk polycrystalline materials [2,3], polycrystalline thin films [4][5][6], and thin films with reduced epitaxy [7,8]. It was established that the control of crystallinity perfection of thin manganite films, such as epitaxial strain or granularity, could be utilized for tuning of their MR properties, especially of LFMR [6][7][8].…”

“…Refs. [5,6]). The substrates were monocrystalline plates (i) of Y-stabilised ZrO 2 (100) (YSZ) and (ii) of silicon buffered by YSZ layers.…”