Direct observation of electronic domains in manganites by spatially resolved spectroscopy

The science of manganites is characterised by a close interplay between charge, spin and lattice degrees of freedom [1-3], arising from the similarities in the energy scales associated with each of these. Besides giving rise to spectacular phenomena [2], such as the colossal magnetoresistance, charge ordering, electronic and magnetic transitions induced by a variety of impulses (composition, temperature, magnetic field and photon field, to name a few), it has been recently realised that phase coexistence plays a very important role in controlling the properties of these materials. It is believed that many of these manganites contain an intricate mixture of different phases, typically a ferromagnetic metallic phase along with an antiferromagnetic insulating phase, at a sub-micron level. These have been probed both structurally using transmission electron microscope (TEM) [4] and magnetically using Lorentz force TEM techniques [5] and magnetic force microscopy [6]. Interestingly enough,there is so far no microscopic investigation that direc tly addresses the issue of metallic or insulating behaviour of these observed textures, though this phenomenon is known as the electronic phase separation, implying an inhomogeneous distribution of electrons in the matrix.