Mixed‐Valence Perovskite Thin Films by Polymer‐Assisted Deposition

Abstract

In thin films of rare‐earth manganites, RE1−xMxMnO3 (RE=rare earth, M=Ca, Sr, Ba), with mixed‐valence perovskite structure, the transport properties highly depend on the deposition technique, processing conditions, and the substrate used. Chemical solution deposition techniques provide many advantages, such as low cost, easy setup, and coating of large areas. However, the crystalline quality, uniformity, and reproducibility of the film depend on the reactivity of the chemical used for solution preparation. In this paper, we report a novel process to grow rare‐earth manganite films using low‐cost polymer‐assisted deposition technique. In this process, polymer controls the viscosity and binds metal ions, resulting in a homogeneous distribution of metal precursors in the solution and a uniform film. These solutions were stable, and crack‐free films were obtained using these solutions. In this paper, thin films of La1−xSrxMnO3, La1−xCaxMnO3, and Pr0.5Ca0.5MnO3 were grown on (001) LaAlO3 substrates. The La1−xSrxMnO3 and La1−xCaxMnO3 films were highly c‐axis oriented and epitaxial, and showed high magnetoresistance near their Curie temperature. Charge ordering was observed in the Pr0.5Ca0.5MnO3 film at 220 K and high magnetoresistance of nearly −100% was obtained at low temperatures. The structural, transport, and magnetic properties of these films were similar to those obtained for films grown by physical vapor deposition.

Epitaxial La0.7Sr0.3MnO3thin films on silicon with excellent magnetic and electric properties by combining physical and chemical methods

“…Among CSD techniques, we selected polymerassisted deposition (PAD) [31][32][33] because it is one of the most suitable processes to produce high-quality epitaxial complex and multilayer structured films [34]. In particular, high-quality epitaxial LSMO thin films were synthetized on single crystal-substrates by PAD [35,36] with a perfect control of the thickness [37] to prepare multilayers controlling their magnetoresistive response [38] and tunnel junctions [39]. PAD is a softchemistry technique that uses branched polymers to coordinate and stabilize different cations in an aqueous solution, which is therefore homogeneously spin-coated on a substrate [40].…”

Low‐Field Magnetoresistance in La0.67Sr0.33MnO3:ZnO Composite Film

“…Hole‐doped pervoskite manganites such as La 1‐x Sr x MnO 3 (LSMO) have been of great interest due to their complex magneotransport properties. In these manganites intrinsic colossal magnetoresistance (CMR), which is a gigantic decrease of resistance by the application of an external magnetic field, is observed near the Curie temperature ( T c ) with high applied magnetic fields (≥1 T) 1–3. Recently, there has been considerable research in order to achieve high magnetoresistance (MR) values with lower magnitude of the applied magnetic fields (<1 T) by taking the advantage of the extrinsic MR effect 4–6.…”

Preparation of metal oxide thin films from organic-additive-free aqueous solutions by low-speed dip-coating

“…3 Jia et al suggested a polymer-assisted deposition (PAD) method, where the addition of organic polymers such as poly(ethyleneimine) (PEI) with ethylenediaminetetraacetic acid (EDTA) prevents the metal ions from engaging in unwanted chemical reactions, and maintains the desired viscosity of solutions for controlling lm thickness, resulting in the deposition of metal oxide lms from aqueous solutions. [4][5][6][7][8][9][10][11][12][13] These synthetic routes assisted by organic polymers would allow us to achieve many kinds of metal oxide lms from aqueous solutions of metal salts.…”