Effects of substrate-induced-strain on the structural and transport properties of La0.7Ca0.3MnO3 thin films

Abstract

We have studied the structural and electrical properties of epitaxial La 0.7 Ca 0.3 MnO 3 (LCMO) thin films prepared by metal organic deposition under different types and degrees of substrate-induced strain. 40-nm-thick films have been epitaxially grown on single-crystalline (LaAlO 3 ) 0.3 -(SrAlTaO 6 ) 0.7 (negligible tensile strain), SrTiO 3 (tensile strain) and LaAlO 3 (compressive strain) substrates. Highresolution X-ray diffraction and reciprocal space maps demonstrate a direct correlation between the crystalline quality and the substrate-induced strain. The electrical properties were found to be strongly dependent on the substrate used. The temperature dependence of resistivity curves was fitted using various approaches in different phases (below and above the ferromagnetic transition temperature T P ). In the ferromagnetic metallic phase, ρ(T ) follows a T α power law. The obtained values of the coefficient α (3.5-4) indicate that the electrical transport in our films is a combination of spin wave scattering processes and electron-magnon or twomagnon scattering phenomena. In the paramagnetic insulator phase, the activation energy E A and the variable range hopping characteristics (characteristic temperature T 0 ) were found to be strongly dependent on the strain-induced lattice mismatch between the LCMO and the substrate used.

Influence of Grinding Particle Size on Structure and Electrical Properties of La0.67Sr0.33MnO3−δCompound

“…In FM region, the charge transport is governed by different scattering activities that induced from the variant dopants, end-sample processing, and end-sample form as well. These scattering process may be the electron-electron ( T 2 ) [20], single magnon ( T 2 ' 5 ) [7], spin-wave ( T 35 ) [21], two-magnon ( T 45 ) [5], or electron-phonon ( T 5 ) [2]. In our case of La 067 Sr 033 MnO 3-polycrystalline samples, we have in turn fitted the present resistivity data to the above terms but they were unsatisfied.…”

Strain-modulated Mott transition in EuNiO3ultrathin films

“…Additionally, the epitaxial relation has been used to stabilize new structural and electronic phases in the form of ultra thin films of coherently strained materials 12 . In such epitaxially stabilized structures, the effect of the lattice modulation on the materials properties can be quite dramatic 13,14,[16][17][18][19][20][21][22][23][24][25][26][27] and is of particular current interest as applications continue to accelerate towards ultra-thin films and heterostructures.The rare-earth (RE) nickelates RNiO 3 (R = Pr, Nd, Eu, ...) in their bulk form, with Ni having formal +3 oxidation state (t 6 2g e 1 g ), all, except for R = La, display a metal-insulator transition, while the nature of the transition and its temperature (T M IT ) depends strongly on the choice of the rare-earth cation as shown in Fig. 1 28-30 .…”

Metastable magnetic state and magnetotransport in disordered manganite thin films

“…Moreover, the substrate induced strain (lattice mismatch $1.8%) can also produce similar results in thin films of LCMO and similar compounds. 35,36 Thickness of our samples is about 80 nm, so the substrate induced strain effect also cannot be completely ruled out, since very small strain has been known to give rise the phase coexistence in perovskite manganites. 37 The absence of M-I transition and yet an observation of magnetic transition at 125 K in the LCMO15 sample can be accounted to the combined effect of chemical disorder created by Al doping, oxygen vacancy, and substrate induced strain, which lead to formation of coexisting metallic ferromagnetic and insulating antiferromagnetic phases.…”