Magnetoconductance and hysteresis in milled La0.67Sr0.33MnO3 powder compacts

Magnetic and magnetotransport properties are presented for a series of La2/3Sr1/3MnO3 powder samples with different grain sizes produced by high-energy ball milling. The magnetoconductivity shows a typical low field contribution superimposed on a linear high field dependence. In grain sizes of several microns the field value HP at which the conductivity is minimized is substantially larger than the coercive field HC indicating that the process of interfacial spin alignment which governs the magnetoconductive response is decoupled from that in the bulk of the grain which defines the magnetization hysteresis. In intensively milled samples, having grain sizes approaching the single domain size, the values of HP and HC converge and low field magnetoconductivity scales with 13M2.