Appl. Phys. Lett. 87, 083102 (2005)

O. Céspedes, S. M. Watts, J. M. D. Coey, K. Dörr, and M. Ziese

Abstract

We have studied the transport properties of mechanically stable Fe₃O₄ andLa_0.7Sr_0.3MnO₃ nanoconstrictions patterned by focused ion-beam milling. The magnetoresistance decreases with the square of the applied voltage and scales with the resistance of the constriction, with values up to 8000% for magnetite and 100% forLa_0.7Sr_0.3MnO₃. These results are interpreted within a model for domain-wall magnetoresistance. Some samples exhibit electrical hysteresis with discrete changes of resistance that disappear in the presence of a magnetic field, indicating domain-wall displacement driven by a spin-polarized current.