Hall effect, magnetoresistance, resistivity and size effect in Ni

Abstract

The low temperature Hall effect, transverse magnetoresistance (with B both parallel and perpendicular to the surface of the plate sample) and electrical resistivity has been measured as a function of temperature and sample thickness on a high purity (residual resistivity ratio ≈ 2200 1 ) polycrystalline Ni plate. The thickness was varied from 1.005 to 0.041 mm by electropolishing and the measurements were made at 1.85, 4.15, 14.1 and 20.1°K. The electrical resistivity was studied in greater detail between 1.75–4.15°K and 14.1–20.1°K. Above magnetic saturation the Hall resistivity is linear in B at 1.85 and 4.15°K but is not linear at 14.1 and 20.1°K. At the lowest temperatures the electrical resistivity varies as T 2. The only appreciable size effect appeared in the magnetoresistance at 1.85 and 4.15°K with B perpendicular to the plate. Four other samples of varying thickness were prepared by cold rolling. This mechanical work is shown to influence the galvanomagnetic properties. The results are discussed.