Resistance Anomaly and Negative Magnetoresistance inn-Type InSb at Very Low Temperatures

The electrical resistivity and the magnetoresistance in $n$-type InSb containing more than 1.8×${10}^{14}$ ${\mathrm{cm}}^{-3\mathrm{}}$ carriers have been measured from 4.2 to 0.1°K. The resistivity increases logarithmically as the temperature is lowered and the relation $\rho =a-b{log}_{10}(T+T_0)$ is obtained experimentally, where $a$, $b$, and $T_0$ are parameters which depend on the carrier concentration. The magnetoresistance at low magnetic field is negative and does not depend on the direction of the magnetic field. The temperature dependence of the magnetoresistance also includes a parameter ${T_0}^{\prime }$ which is nearly equal to $T_0$ in each sample. Interpretations of the experimental results are made on the basis of the localized-spin model. As a result, it is concluded that the conduction-electron scattering by the localized spin through an $s-d$ exchange interaction may be dominant at very low temperatures in $n$-type InSb with low carrier concentration, and that an antiferromagnetic interaction between localized spins may exist. A $g$ factor of the localized spin which is expected to be a few times larger than that of the isolated donor electron suggests that the localized spins arise from the same origin as discussed by Toyozawa.