Temperature dependence of carrier-nucleus interactions in semimetallic antimony

Previous 121Sb relaxation measurements in pure antimony metal show a typical metallic (Korringa) temperature dependence of the nuclear spin}lattice relaxation rate at low temperatures, followed by a quadratic temperature dependence above the Debye temperature. This deviation was previously ascribed to the onset of signi"cant phononinduced relaxation. In this paper, nuclear spin}lattice relaxation of both 121Sb and 123Sb has been investigated over the temperature range 4}435 K using pulsed NQR. These two-isotope data allow for a decisive investigation of the importance of quadrupolar relaxation mechanisms over a wide temperature range. Our results show that the ratio of quadrupole to magnetic transition rates changes from a fraction of a percent to order 1% as the temperature is increased through the Debye temperature, but this change cannot account for the observed deviation from Korringa behaviour. The relaxation data, therefore, suggest a signi"cant temperature dependence of the carrier properties of antimony. Possible explanations for the high-temperature behaviour are discussed in terms of the electronic structure of antimony. ( 2000 Elsevier Science B.V. All rights reserved.