Staircase effect in metamagnetic transitions of charge and orbitally ordered manganites

This paper reports on peculiar metamagnetic transitions which take place in antiferromagnetic, charge and orbitally ordered (AFCOO) manganites. At very low temperatures, the virgin magnetization curves of some of these compounds exhibit several, sharp steps giving rise to a staircase-like shape. This staircase effect is shown to be sensitive to various experimental parameters. Several potential interpretations of the staircase effect are discussed in relation to this set of results. A martensitic-like scenario, involving a leading role of the structural distortions associated to the collapse of the orbital ordering, is found to be the most plausible interpretation.