Magnetoresistance and magnetostriction effect of (La1−xSmx)2/3Sr1/3MnO3 manganites

A series of bulk polycrystalline (La1−xSmx)2/3Sr1/3MnO3 ( x = 0.0 , 0.2 , 0.4 , 0.6 , 0.7 ) samples were prepared by traditional solid-phase reaction method. Their structures, magnetoresistances and magnetostrictions were studied. The experimental results indicate that with the increase of the Sm content x , the average ionic radius of the A site 〈 r A 〉 and the Curie temperature of the samples decrease, the maximum of the zero-field resistivity at T P and corresponding magnetoresistance increase. The magnetostriction measurement shows that the anisotropic magnetostriction coefficient λ t are nearly zero, while the volume magnetostriction coefficients are negative for the x = 0.6 and 0.7 samples, which implies that the volumes of the samples are contracted at the temperature just below the Curie temperature, and no saturation occurred even under 7 T strong magnetic field. For the x = 0.6 sample, the maximum of ω is −550×10−6 in the magnetic field of 7 T at 210 K. These experimental results can be interpreted by the viewpoint of phase separation due to the substitution of Sm3+ with smaller ionic radius for La3+ with larger ionic radius in the samples.