Wednesday, January 18, 2012

Violating a text book rule

Solid state physics text books tell us that Matthiessen's rule is obeyed by simple metals: the temperature dependent resistivity is the sum of a temperature independent term due to elastic scattering off impurities and an impurity independent term which is temperature dependent due to inelastic scattering. I teach this to undergrads, but have struggled to actually find experimental data to show them.

Yesterday I came across a 1944 paper by Fairbank which contained the figure below for copper with tin impurities:
It looks pretty convincing. However, the text points out that the temperature dependence actually varies significantly with the impurity concentration, in violation of Matthiesens rule!
Does anyone know of better data?
Any simple explanations for these deviations?

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