Thickness effects on the magnetic and electrical transport properties of highly epitaxial LaBaCo2O5.5+δ thin films on MgO substrates

Abstract

The transport properties of double perovskite LaBaCo2O5.5+δ thin films with different thicknesses were systemically studied. A thin (7 nm in thickness), disordered LaBaCo2O5.5+δ layer was formed at the interface between the film and substrate. The films had a typical semiconductor behavior with antiferromagnetic and ferromagnetic behavior coexisting at low temperature. Although the Curie temperature was independent of the film thickness, the coercive fields and magnetizations increase with increasing the film thickness. An ultra large magnetoresistance effect value of about 44% was obtained at 60 K for the film of 82 nm.

Ultrafast Atomic Layer-by-Layer Oxygen Vacancy-Exchange Diffusion in Double-Perovskite LnBaCo2O5.5+δ Thin Films

“…1 (b) can be formed in the forms of order and disorder structures. Recently, highly epitaxial thin films of single-crystalline LnBCO (Ln = La, Er, Pr) were grown on (001) LaAlO 3 by using pulsed laser deposition with a KrF excimer pulsed laser1213141516. The oxidation and redox reactions of these films were monitored by measuring their resistance R under a switching flow of O 2 and H 2 as a function of the gas flow time t. The ac conductivity measurements indicate that both oxidation under O 2 and reduction under H 2 can occur at the temperature as low as ~200°C.…”

Nanodomain induced anomalous magnetic and electronic transport properties of LaBaCo2O5.5+δ highly epitaxial thin films

“…This is in good agreement with the X-ray diffraction result from our previous report. 28,29 Weak diffraction spots at the midpoints between two strong spots can be seen in Figures 2(a) and 2(c) (identified with arrows in the SAED patters) indicating the formation of nanoscale regions of ordered tetragonal structure 28 or of the ordered oxygen vacancy structure in the LBCO film.…”

“…The temperature dependence of the electrical resistance of LBCO thin film on MgO measured under the applied magnetic fields from 0T to 7T is shown in Figure 1, similar to our previous work. 28,29 The magnetoresistance, MR (%), is defined as MR (%) ¼ [R(H) À R(0)]/R(0) Â 100%, where R(H) is electrical resistance under the magnetic field and R(0) is at zero magnetic field, respectively. The films show typical semiconductor behavior in the measurement temperature range.…”

Magnetic and Electrical Transport Properties of LaBaCo2O5.5+δ Thin Films on Vicinal (001) SrTiO3 Surfaces

“…13−16 A large magnetoresistance (MR) effect (19%) was observed for the LaBCO films grown on (001) SrTiO 3 , and a much greater MR effect (54%) for those grown on (001) MgO. 17 These results indicate that the interface strain in the highly epitaxial LaBCO thin films can significantly alter the physical properties of the films such as low-temperature magnetization, MR, 16,18 and high-temperature electrical transport properties. 14,15 Besides strain generated from the lattice misfit between the substrate and the LaBCO film, the substrate surface structures such as surface step, terrace, kink sites as well as other defect distribution are also important factors affecting the microstructures and the physical properties of the films.…”