Magnetoresistance of Iron Whiskers

Abstract

Transverse magnetoresistance measurements on iron whiskers with axes along $〈100〉$, $〈110〉$, and $〈111〉$ have been made in fields up to 50 kOe. Measurements have been made on whiskers with diameters ranging from 40 to 400 \ensuremath{\mu}. Sharp minima observed in the rotation diagrams measured at 50 kOe for all three orientations are consistent with the existence of open orbits along $〈100〉$ and $〈110〉$ directions. The field dependence curves show a region of negative magnetoresistance at low fields and at high fields the resistance varies as ${B}^{m}$, where $1<m<2$. The extent of the negative magnetoresistance region depends both on the field orientation and the diameter of the whisker and appears to be correlated with the domain structure. A size effect has also been observed on the field dependence of resistance at high fields and on the residual resistance ratio $\frac{{\ensuremath{\rho}}_{\mathrm{RT}}}{{{\ensuremath{\rho}}_{4.2}}^{\ensuremath{\circ}}}$. Values of $\frac{{\ensuremath{\rho}}_{\mathrm{RT}}}{{{\ensuremath{\rho}}_{4.2}}^{\ensuremath{\circ}}}$ range from 200 to 2000 for the whiskers which have been measured.