Galvanomagnetic size effects in iron whiskers

The influence of sample dimensions on the resistance and magnetoresistance (both longitudinal and transverse) was studied in iron whiskers with square cross section of dimensions 1÷10 μm. The effective electron mean free path of bulk material of corresponding purity was determined to be λ_∞ ～40 μm. The results are analyzed in terms of available theoretical predictions which are mostly based on spherical Fermi surface models; this allows to determine two additional effective parameters of the Fermi surface. The temperature dependence of transverse magnetoresistance leads to the conclusion that surface scattering has diffuse character. This is discussed with regard to earlier experimental work on metal whiskers and to recent interpretation of both diffuse and specular scattering in tungsten byPanchenko et al.