This paper reports measurements of the magnetic field and temperature dependence of the Hall coefficient of both single-crystal and polycrystalline indium in the regime characterized by ${\omega }_c\tau <1\mathrm{}$. Measurements were performed at temperatures below 4.5°K using the helicon-wave technique. The normally positive Hall coefficient was observed to reverse sign at fields below a few hundred gauss with the field H oriented along the [100] and [111] crystal axes. The magnitude of the "crossing field" $H_0$ as well as the zero-field coefficient $R\left(0\right)\mathrm{}$ was observed to decrease with increasing temperature. We have analyzed our results in terms of a two-band model of the Hall coefficient and have concluded that the ratio of the electron relaxation time to the hole relaxation time is less than unity and decreases with increasing temperature.

• Received 24 March 1969

DOI:https://doi.org/10.1103/PhysRev.185.1009