Indian Journal of Engineering & Materials Sciences Vol. 14, April 2007, pp. 163-166 Strain induced non-linear conduction in epitaxial La 0.7 A 0.3 MnO 3 manganite thin films P S Vachhani, P S Solanki, J H Markna, R N Parmar, J A Bhalodia & D G Kuberkar* Department of Physics, Saurashtra University, Rajkot 360 005, India Received 19 July 2006; accepted 20 February 2007 In this paper, the current-voltage (I-V) properties of La 0.7 A 0.3 MnO 3 (A = Ca, Sr, Ba) manganite thin films grown on single crystalline LAO (100) substrate using chemical solution deposition (CSD) technique have been reported. Epitaxial nature of all the films has been confirmed from XRD measurements. The I-V measurements carried out on La 0.7 Ba 0.3 MnO 3 (LBMO) films show an unusual non-linear transport behaviour contrary to that observed for La 0.7 Ca 0.3 MnO 3 (LCMO) and La 0.7 Sr 0.3 MnO 3 (LSMO) films. This non-linearity has been explained in terms of non-uniform strain distribution resulting due to mismatch in the lattice parameters of LBMO film and substrate. The conductance data for all the films have been fitted using Simmon’s model and the possible mechanism of charge conduction in the films has been discussed. IPC Code: H01F10/00 There has been extensive research work carried out on the manganites having general formula R 1-x A x MnO 3 (R= rare earth trivalent cation, A= divalent cation). These systems exhibit dual novel properties such as negative colossal magnetoresistance (CMR) and the metal-insulator (M-I) transition in the vicinity of magnetic transition (paramagnetic to ferromagnetic) which have been explained in terms of correlation between spin, charge and orbital degrees of freedom 1 . It is well-known fact that, Zener-double exchange (ZDE) is responsible for the ferromagnetic metal to paramagnetic insulator (FMM-PMI) transition but one cannot account that this is the only reason for the FMM-PMI transition 2 . The Jahn-Teller (JT) distortion should be considered along with the ZDE which suggests that, the lattice distortion caused by Mn 3+ ion (bond stretching in the MnO 6 octahedra) also plays a crucial role in M-I transition and the suppression in resistivity 3 . Moreover, since last few years the efforts have been made on the fabrication of devices based on manganite thin films and multilayers, having potential applications. To understand the transport behaviour of such devices, I-V characteristics emerge as a most comprehensive tool. There are few reports on the creation of an artificial grain boundaries on the thin film structures by depositing the films on the bi- crystal substrates 4,5 . Studies on effect of grain boundaries in La 1-x (Sr/Ca) x MnO 3 thin films grown on bi-crystal substrates suggest that, the transport properties of the film cannot be fully explained by tunnelling across grain boundary 5 . Gunnarsson et al. 6 have demonstrated the model for spin-polarized transport through artificial grain boundary created by bi-crystal substrates which correlates the magneto- resistance value with the potential barrier at the grain boundary. Khare et al. 7 have investigated the conduction through an artificial grain boundary junction made in LBMO thin film with optimal doping. In the course of present studies, all the manganite thin films were grown using simple and faster chemical solution deposition (CSD) technique which yield high quality epitaxial films of desired thickness. The advantage of CSD technique for thin film growth over the other techniques is in its requirement of low reaction and annealing temperatures and cost effectiveness. In this communication, the results of the temperature dependent I-V studies on LCMO, LSMO and LBMO manganite thin films grown by CSD method have been explained and the results obtained have been discussed in the context of possible conduction mechanism. Experimental Procedure The La 0.7 A 0.3 MnO 3 (A = Ca, Sr, Ba) thin films were grown by dissolving the constituent acetates in a mixture of acetic acid and water to obtain precursor _________________ *For correspondence: (E-mail: dgkuberkar@rediffmail.com; dgk@icenet.net)