Abstract:
We have used tunnelling spectroscopy (TS) to probe the density of states (DOS)
of the rare earth manganate Nd0:5Sr0:5MnO3, which shows a transition to a charge ordered
(CO) antiferromagnetic insulating state from a ferromagnetic metallic state. We find that a
gap opens up in the DOS around the Fermi level, EF , as the solid is cooled below the charge
ordering temperature TCO. The charge ordering gap (1CO) was found to be strongly temperature
dependent for T∼TCO and for T/TCO < 0:6 it reaches a limiting value of nearly 0.27 eV.
Above TCO the temperature dependence of the DOS at EF was found to be similar to that of the
solids such as La0:8Ca0:2MnO3 which show colossal magnetoresistance but no charge ordering.
