Correlation between structural defects and properties in large La–Sr–Mn–O single crystals

Structural, magnetic, and electrical properties of La0.8Sr0.2MnO3 single crystals grown by the floating zone technique have been investigated using x-ray Laue diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy and magnetic force microscopy (MFM) magnetization and resistivity measurements. The aim of this work was to identify growth defects and their possible correlation with the transport properties or magnetic self-organization. The analysis by x-ray Laue diffraction and SEM reveals large single crystal structure without any extended microdefects and with a homogeneous composition. TEM observations show nanometric defects present only in the central part of the grown rod and allow to identify these defects as nanocracks resulting from a high stress gradient during the growth. Transport measurements indicate that there is an effect of the variation of oxygen content but the conducting behavior between 300 and 5K is not affected by the prese...