Effect of nano-oxide layers on the magnetoresistance of ultrathin permalloy films

Abstract

Ta/NiFe/Ta ultrathin films with and without nano-oxide layers (NOLs) were prepared by magnetron sputtering followed by a vacuum annealing process. The influence of NOLs on the magnetoresistance (MR) ratio of ultrathin permalloy films was studied. The results show that the influence of grain size and textures on the MR ratio becomes weak when the thickness of the NiFe layer is below 15 nm. A higher MR ratio was observed for the thinner (< 15 nm) NiFe film with NOLs. The MR ratio of a 10 nm NiFe film can be remarkably enhanced by NOLs. The enhanced MR ratio for these ultrathin films can be attributed to the enhanced specular reflection of conduction electrons.

Study on magnetism of Pr0.45(Ca1−x Sr x )0.55MnO3 samples

“…For example, paramagnetic (PM) phase, ferromagnetic (FM) phase, antiferromagnetic (AFM) phase and their complicated competition relation exist in the system when x ≤ 0.5. In this range, random phase separation leads to famous colossal magnetoresistance [3][4][5]. On the other hand, in the high doped manganite with x ≥ 0.5, when the temperature is lower than charge ordering temperature T CO , the system exhibits orbit ordering and charge ordering, and it is accompanied by the appearance of antiferromagnetic basic state [6].…”