Anomalous magnetoresistance of Bi doped La0.67Sr0.33MnO3

N. Kambhala, S.S. Samatham, R. Venkatesh, V. Ganesan, S. Angappane
Phys. Status Solidi B, 1700194 (2017); (DOI: 10.1002/pssb.201700194).

Temperature dependence of the resistance with different applied magnetic fields, H= 0, 5 and 10 T of La0.67-xBixSr0.33MnO3 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5).

We have studied the magnetotransport properties of La_0.67-xBi_xSr_0.33MnO₃ (x=0, 0.3, 0.4, 0.5). The x ≤ 0.3 samples show the metal-insulator transitions, while x ≥ 0.4 samples exhibit an insulating behaviour at zero field. Notably, two low-temperature upturns observed for La_0.37Bi_0.3Sr_0.33MnO₃, which indicates the existence of two different mechanisms. La_0.27Bi_0.4Sr_0.33MnO₃ shows the field induced metallic behaviour due to the melting of charge ordering with applied magnetic field. The large magnetoresistance of ~ 100 % was observed for La_0.27Bi_0.4Sr_0.33MnO₃ at ~ 90 K. On the other hand, La_0.37Bi_0.3Sr_0.33MnO₃ exhibits a nearly constant large MR of ~ 80 % between ~ 30 and 250 K, which decreases out-side this temperature range. The observed anomalous low-temperature magnetotransport properties of La_0.67-xBi_xSr_0.33MnO₃ is shown to arise from the coexisting phases of ferromagnetic metallic and antiferromagnetic charge ordered insulating states.