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We have investigated nanometric magnetic textures in thin (<150 nm) plates of Ru-doped bilayered manganites La1.2Sr1.8(Mn1-yRuy)2O7. Ru substitution for Mn site changes the magnetic anisotropy from in-plane to out-of-plane easy axis type without any significant change of global magnetic and crystal structures. The combination of conventional and Lorentz transmission electron microscopy observations confirms the emergence of magnetic bubbles and skyrmions in the absence of magnetic field. With the changing Ru concentration, systematic changes in the type of magnetic bubbles are observed. A tiny residual magnetic field also affects the generation and the type-change of magnetic bubbles. [ABSTRACT FROM AUTHOR]

The spatial fluctuation of the magnetic domain (MD) and charge/orbital ordering (CO/OO) structure at around the Curie temperature (TC) was directly observed in a colossal magnetoresistance (CMR) compound, La0.69Ca0.31MnO3, in which extraordinary anisotropic magnetoresistance (AMR) has also been observed. It was found that the long range MD structure collapses upon the emergence of short range CO/OO in a narrow temperature regime, which provides abundant evidence in support of a gain in magnetoresistance at around TC. Moreover, the pinning effect on the MD wall was discerned and it may contribute to the CMR as well as to the extraordinary AMR effect. [ABSTRACT FROM AUTHOR]

Imaging of charge/orbital ordering (CO/OO) structure and canted antiferromagnetic (AFM) domain structure in Sm1-xSrxMnO3 (x=0.55 and 0.6) has successfully been demonstrated. In the x=0.55 compound, the commensurate CO/OO structure with modulation vector Q=(0,1/3,0) was observed above the AFM transition temperature (TNA∼180 K). This modulation structure changes to an incommensurate one below TNA. In the x=0.6 compound, the typical 180° magnetic domains were observed in the (110) plane below 50 K indicating the canted AFM structure. This AFM structure locally collapses because of the existence of the short-range CO. [ABSTRACT FROM AUTHOR]