2Deparment of Physics,University of Cambridge,Cambridge,

During the past few years,the manganites haveundergone a second renaissance.These perovskiteoxides of manganese first rose to prominence when it was discovered1 in 1994 that large changes in electrical resistivity could be brought about by an applied magnetic field,a phenomenon known as colossal magnetoresistance.Unfortunately,magnetoresistance effects in the manganites are strongly temperature dependendent.This,together with several other factors, has prevented the commercial exploitation of manganites in devices such as disc-drive read-heads. But fundamental and practical interest in the manganites is resurgent once more,because modern imaging techniques have revealed that the electronic and magnetic properties possess spatial variations over a wide range of length scales.These magnetic and electronic textures are poorly understood at present,but b