Effects of Ga doping in La2/3Sr1/3MnO3

Abstract

We substitute Ga for Mn in the La2/3Sr1/3MnO3 compound to see how magnetic and atomic disorder affects the properties of this system. Ga doping gives rise to minor structural effects in the La2/3Sr1/3Mn1−xGaxO3 (0<~x<~0.5) series. However, the Curie temperature and the temperature at which the resistivity changes its behavior from insulating- to metallic-like both decrease drastically with increasing Ga content. In addition, these transitions do not occur at the same temperature for x>0.02. Ferromagnetic long-range order is observed for samples with x<0.3. For x>0.3, the system is in a spin-glass-like state. We obtain rather high values of negative magnetoresistance in x<~0.2 samples, which likely arises from spin-polarized tunneling.