Strain effects on the electric and magnetic properties of the magnetoresistive La_0.7Ba_0.3MnO₃ films

We have synthesized (100) La_0.7Ba_0.3MnO₃ films on SrTiO_0.3(STO),NdGaO_0.3 (NGO}) LaAlO_0.3 (LAO}), and MgO substrates using pulsed laser deposition and investigated their electric and magnetic properties. The structural, electric and magnetic properties of the LBMO films seemed to be dependent on lattice mismatch between LBMO and the substrate. The characteristics of the LBMO film on STO with negligible lattice mismatch were close to those of the bulk LBMO. Interestingly, the uniaxial-type stress acting on the LBMO film by the NGO substrate induced a distinctive difference in the magnetic hysteresis and the magnetoresistance curves measured for two orthogonal in-plane directions. A sudden drop of ∼ 0.6% in the low field magnetoresistance curve of the LMBO on the NGO is probably related to spin dependent scattering of charge carriers going through magnetic domains or grains. On the other hand, the LAO and the MgO substrates with a large lattice mismatch of >5% did not effectively induced homogeneous lattice strain to the LBMO film.