Multi-band effect in the noncentrosymmetric superconductors Mg₁₂₋δIr₁₉B₁₆ revealed by Hall effect and magnetoresistance measurements

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We report the longitudinal resistivity and Hall effect measurements on the noncentrosymmetric superconducting Mg₁₂₋δIr₁₉B₁₆ samples with different critical transition temperatures. A strong temperature dependence of the Hall coefficient Rₕ and nonlinear magnetic field dependence of the Hall resistivity ρxy in wide temperature region are observed, suggesting a strong multi-band effect in this system. Moreover, a large magnetoresistance up to 20% is found at the field of 9 T. We also observe the violation of the Kohler's rule from our magnetoresistance data, further confirming the presence of multi-band effect in our samples. A detailed analysis shows that the data can't be simply described within the two-band scenario at low temperatures, so we argue that there may be more than two bands contributing to the conduction of the samples.