Electro-resistive Memory Effect in Colossal Magnetoresistive Films and Performance Enhancement by Post-annealing

Abstract

Colossal magnetoresistive thin films have shown a large electric-pulse-induced resistivity change effect in zero magnetic field and at room temperature. The resistance of such films can be both decreased and increased through multiple nonvolatile intermediate levels by short electrical pulses. The effect provides a potential to develop a novel nonvolatile memory with high density, fast speed, and low power-consumption. An example of this effect has been seen for Pr0.7Ca0.3MnO3 films within which the thermal behavior of the film revealed a method for signal enhancement through annealing. An increase of 700% of the resistance ratio has been demonstrated for a film annealed at 170oC for 30 min. The effect is also observed to be active at room temperature but inefficient at low temperatures, which is interestingly contrary to the behavior of the colossal magnetoresistance effect and provides a clue to understanding the effect.

Unusual current‐voltage characteristics of single crystalline and bicrystalline La0.7Ca0.3MnO3 films

“…This effect was indeed already observed for Pt/Pr 1−x Ca x MnO 3 /Pt heterostructures, in which the current was biased across the film, i.e. parallel to the substrate normal [11]. But whereas in these studies the contacts were only separated by 0.5-2 µm and such that charge injection effects are important [11], in the configurations used in our experiments, the transport properties of the manganite films are measured tens of micrometers away from the contacts.…”

“…parallel to the substrate normal [11]. But whereas in these studies the contacts were only separated by 0.5-2 µm and such that charge injection effects are important [11], in the configurations used in our experiments, the transport properties of the manganite films are measured tens of micrometers away from the contacts. Therefore nonequilibrium effects caused by charge injection from the contacts seem implausible.…”