Magnetic-field-induced superconductivity?

It is shown that a giant negative magnetoresistance effect in doped manganites can be explained using a model developed earlier to explain high-temperature superconductivity, based on allowance for the covalence of the transition metal-oxygen bond. This effect is caused by delocalization of π-electrons along asymmetric π-orbitals belonging to chains of covalently coupled Mn and O ions. Unlike high-temperature superconductors, in manganites this delocalization is induced by a magnetic field which ferromagnetically orients unpaired π-electrons and thereby lifts the restriction against their collective motion along the π-orbital when the manganese ions are ferromagnetically ordered.