engleski

Origin of the maximum in the temperature-dependent electrical resistivity of quasicrystals

Many quasicrystalline samples exhibit a maximum in the temperature-dependent electrical restivity, the effect being especially pronounced in the icosahedral AlPdMn family. We discusse the origin of this phenomen from both, the experimental and theoretical point of view and show that it can be consistently explained as a magnetic effect due to presence of localized magnetic scattering centers within the quasiperiodic lattice. On the experimental side we present a comparative electrical resistivity-magnetic susceptibility study of three icosahedral samples and show that the temperature of the electrical restivity maximum exhibits a one-to-one correlation with the magnitude of the electronic paramagnetic magnetization of localized centers. On the theoretical side we first discuss the appearance of the electrical resistivity maximum within the existing models of electrical conduction in quasicrystals. While the variable-range hopping conuctivity models do not predict the maximum in electrical resitivity, the quantum interference effects predict a maximum due to weak localization of electrons, which, hoever, is not directly related to the magnetism of quasicrystals. Next we show that the maximum in electrical resistivity of magnetic origin is predicted by the Korringa-Gerritsen model, originally developed for noble metals with diluted transition metal impurities. The Korringa-Gerritsen model correctly predicts the shift of the electrical resistivity maximum to higher temperatures for more magnetic samples and qualitatively reproduces the experimental electrical resistivity curves of quasicrystals, both magnetic and nonmagnetic. The experimental electrical resistivtiy data are then analyzed with both models-the quantum interference effects and the Korringa-Gerritsen model-and their applicability to quasicrystals is discusssed.

quasicrystals ; electrical resistivity ; magnetic susceptility ; quantum interference effects

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