Surprising resistivity decrease in manganites with constant electronic density

A decrease of eight orders of magnitude in the resistance of.(La0.5Ca0.5)(z)MnO3 has been detected when the electronic density is kept constant while the calcium content is modified by introducing cationic vacancies. This effect is related to the disappearance of the charge ordering state and the emergence of an antiferromagnetic-ferromagnetic transition. Moreover, high values of the colossal magnetoresistance above room temperature are attained.