Enhanced extrinsic magnetoresistance in LaSrMnO3 artificial grain boundaries induced by ion implantation

The resistance of polycrystalline divalent-ion-doped LaMnO₃ has been shown to be highly sensitive to low magnetic fields. To enable direct study of the properties of isolated grain boundaries, we developed a new method to form artificial boundaries in manganite thin films. Metal slits about 70 nm in width were printed by 30 KV focused Ga ion beam nanolithography on a 4 μmLaSrMnO₃ bridge, and the materials in these slits were then irradiated by accelerated H2+ ions. Using this method, magnetoresistance (MR) >8% and >16% were, respectively, obtained at 150 and at 10 K in a magnetic field of 1 T. This technique is very promising in terms of its simplicity and flexibility of fabrication and has the potential for high-density integration.