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Some Remarks on Deviations from Matthiessen's Rule in Dilute Alloy Systems
Author(s) -
Barnard R. D.
Publication year - 1981
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221040226
Subject(s) - condensed matter physics , anisotropy , scattering , fermi surface , electrical resistivity and conductivity , curvature , impurity , phonon , relaxation (psychology) , alloy , electron scattering , electron , phonon scattering , materials science , physics , geometry , quantum mechanics , mathematics , superconductivity , metallurgy , psychology , social psychology
An examination is made of the main features of deviations from Matthiessen's rule in alloy systems from a general standpoint based on anisotropy in the electron–phonon and electron–impurity scattering. It is shown that in virtually all metals at low temperatures, a T 3 or near T 3 contribution to the electron–phonon inverse relaxation time exists due to the geometry of the Fermi surface or from U processes which produce large angle scattering. As a result, such metals at low temperatures will possess considerable anisotropy in the electron–phonon mean free paths associated with the transport properties, which arises purely from the geometry of the transitions. It is further shown that the usually small high curvature regions of the Fermi surface which produce the anisotropy, while not making a large contribution to the resistivity of the intrinsically pure metal, however are of paramount importance when impurity scattering dominates and results in near T 3 variations of the temperature dependent resistivity, ϱ T . Such variations appear to be obeyed almost universally in alloys for which ϱ 0 ≫ϱID. The role of anisotropy in the mean free paths due to gold and dislocations as scattering centres in the silver system is discussed in connection with their failure to adhere to the universal curve of ϱ T versus log ϱ 0 for silver.