Resistivity Minimum in Beryllium Films

Abstract

In the analysis of the resistivity of metals, the classical Boltzmann transport equation fails in the condition that the thermal phonon wavelength is larger than the electron mean free path (called the non‐Boltzmann transport regime), and a quantum kinetic equation must be solved. In such a case, the interference between electron−phonon and electron−impurity scattering (electron−phonon−impurity interference effect) should be considered. Herein, the electrical transport properties of Be films grown via direct current magnetron sputtering are studied. Due to the high Debye temperatures and high impurity/defect concentrations of the Be films, the thermal phonon wavelength is larger than the electron mean free path, indicating the non‐Boltzmann transport. The significant resistivity correction from the electron−phonon−impurity interference effect should be observed in the Be films. In the temperature dependence of the resistivity of the Be films, a resistivity minimum near 90 K is observed. After subtracting the contributions of electron−electron and electron−phonon interactions, the electron−phonon−impurity interference‐contributed resistivity is obtained, which increases with temperature like . The signature of the resistivity contribution from electron−phonon−impurity interference effect is observed in the non‐Boltzmann transport regime.