4. Conclusion

other hand, the influence from certain size effects varies with the doping level. So, a step-shape resistance behavior can be observed for the x = 0.2 sample, which indicates that the metalinsulator transition is not completely suppressed. However, in the x = 0.4 sample, the resistance decreases almost linearly from 5 K to 200 K. Secondly, the x = 0.3 sample with the highest saturation magnetization shows the weakest MR effect, and inversely, the x = 0.2 sample exhibits the strongest MR effect at low temperatures. At 2.5 T, the maximum of the MR is already over 40%, which points to an obvious LFMR effect. The increase of the MR with reducing magnetization has been reported by Balcells et al. [8]. In their work, the variation of the grain size is the main reason of the behavior observed. In contrast to this, there is no obvious grain size difference between our samples. The dependence of the MR on the magnetization requires further investigation. Thirdly, at around 200 K with the doping level x = 0.2 and 0.3, the MR curves at 2.5 T have a crossover with the curves at other fields, which means that above 200 K, the absolute value of the magnetoresistance does not monotonously increase

Figure 9. Magnetoresistance of La0.8Sr0.2MnO3 nanowires as function of the applied field for various temperatures. The

To enable a comparison with data on other LSMO sample types but with the same chemical composition (x = 0.2) published in the literature, we summarize some data at 1 T applied

From Table 2, we see that the nanowire sample x = 0.2 exhibits a larger MR of 20.66% as compared to the nanoparticles and the powder samples of the same chemical composition studied in the literature, however, at some lower temperature. This points clearly to the important contribution of the much smaller LSMO grains in our nanowire network fabric samples, and the additional scattering at the numerous interconnects provides extra MR.

Jugdersuren et al. [19] reported a large LFMR at room temperature in their LSMO nanowires extracted from the networks produced by electrospinning and showed a dependence of the

magnetic field in Table 2 and compare them with our results.

with the external field.

inset gives the LFMR at 0.1 T applied magnetic field.

106 Nanowires - Synthesis, Properties and Applications

Nonwoven nanowire networks of LSMO with three doping levels x = 0.2, 0.3, and 0.4 were fabricated by means of electrospinning. The magnetoresistance effect of these nanowire fabrics was measured up to 10 T applied field between 5 K and 300 K. The reduced dimensions of the nanowires and the large number of interconnects between them were found to increase the MR effect as compared to bulk samples. An MR ratio of 70% was observed for the sample x = 0.2 at low temperatures and 10 T applied magnetic field.
