Magnetotransport properties of spin-glass-like layered compounds La1−xSr1+xCoO4(0⩽x⩽0.40)(0⩽x⩽0.40)

We report the magnetic and transport properties of the cobalt layered mixed-oxides La1−xSr1+xCoO4(0⩽x⩽0.40)(0⩽x⩽0.40). An evolution towards an anomalous “cluster-glass”-like behavior as x   increases has been found. The onset of the ferromagnetic order in the layered phases occurs at around 150 K followed by a blocking process around 125 K. Also, present in the magnetic response of these materials is the signal coming from small intergrowths of a perovskite phase, also detected by TEM, although invisible for powder-X-ray diffraction. From the electrical point of view these materials are semiconducting and their resistivity decreases upon doping. Most interestingly, at low temperature these layered compounds show rather large magnetoresistance (MR). The highest effect is found in the sample with x=0.20x=0.20 that shows a magnetoresistance MRmax=−24%MRmax=−24% at T=15K under a field Hmax=50kOe.

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